Final ReportSummary - IMAGINE (An Innovative, Ultra Low Cost, High Performance, Monolithic Millimeter Wave Imager Module to Increase the Safety of European Citizens)
IMAGINE is a 29 month EUR 1.1 million project supported by the 'Research for SMEs' Seventh Framework Programme of the European Commission. The project brings together expertise from the security, mm-wave scanning, semiconductor and liquid crystal polymer industries from across eight European countries with the task of developing a low cost, monolithic mm-wave imaging module for rapid security screening in mass transportation hubs such as airports.
Protecting its citizens from terrorism is a high priority for the EC. Current state of the art security procedures for air travel have significantly improved airport security. The need is now to protect the softer, unprotected areas such as mass transportation systems and hubs that could be targeted with devastating effect (as was the case in the terrible attacks in e.g. London and Madrid). Such areas are largely unprotected because current security systems are very expensive, bulky and too slow.
Therefore, there is an urgent need for innovative new security screening technology that can provide low cost, high performance, rapid 'walk-by' screening at normal flow rates.
Whilst mm-wave technology is the leading technology, cost is a barrier. The critical part of such systems is the detector module; at a cost of over EUR 1000 per pixel, the imager module accounts for 60 % of the overall system cost. This high cost is due to the cost of semiconductor material and the cost of assembly and tuning to overcome resonance effects.
The IMAGINE project aimed therefore to perform research and development of innovative solutions to increase integration, reduce size and costs, whilst maintaining high performance, for passive mm-wave imager front-end modules which would allow this technology to be deployed for security applications within an increased range of critical locations across Europe.
The project coordinator was GATE S.A. and the project technical coordinator was Acreo.
The block diagram of the passive mm-wave imager front-end module developed for a single pixel is shown below. The main innovation areas for the project were: development of a zero-biased detector diode; development of a low noise amplifier (LNA); MMIC integration of the zero-biased diode and LNA; development of a compact high performance broadband mm-wave antenna; integration of the front-end components into a compact, low cost module based on a high performance LCP carrier.
The project developed a demonstrator that was tested during the final stages of the project in one of GATE's passive mm-wave imaging systems.
This was an extremely challenging project requiring significant scientific knowledge generation and technology development. The SMEs involved did not have all the in-house skills to develop this solution alone and the skill gaps were provided by the RTD performers. The US currently dominates the growing imaging market (USD 49 million, predicted to grow by 1800 % in 5 years) which we aim to access for Europe with this project. Without the research for SME initiative, the SMEs would not have had the financial resources to engage this leading European expertise.
Project context and objectives:
Protecting its citizens from terrorism remains a high priority for the EC. Current SOA security procedures for air travel have significantly improved airport security. The need is now to protect the softer, unprotected areas such as mass transportation systems and hubs which are being targeted with devastating effect. They are largely unprotected since current security systems are too expensive and too slow. Therefore, there is an urgent need for innovative new security screening technology that can provide a low cost, rapid 'walk-by' screening at normal flow rates. Whilst millimetre-wave (mm-wave) technology is the leading technology, cost is a barrier. The critical part of mm-wave systems is the detector module; at a cost of EUR 1125 per pixel the module accounts for 60 % of the overall system cost. At present, this high cost is due to the cost of semiconductor material and the cost of assembly and tuning to overcome resonance effects.
In order for mm-wave imager systems to become competitive for mass transit applications we need to reduce dramatically the cost of the mm-wave detector modules down to around EUR 150 retail price. Lower cost modules will not only enable more scanners to be introduced but will allow a greater number of pixels per scanner, reducing throughput times dramatically. This is clearly an extremely ambitious target and in order to achieve this we will clearly need to overcome all of the aforementioned reasons for high cost. Such a unit will need to have the following characteristics:
i) single semi-conductor wafer containing the low noise amplifier (LNA) and detector (diode). This will overcome the problem of separate interconnections, lengthy assembly and testing time;
ii) optimised semiconductor formulation that exhibits the advantages of both gallium arsenide (GaAs) and indium phosphide (InP) whilst minimising the disadvantages of both;
iii) extremely low cost substrate that does not require lengthy precision engineering from expensive materials;
iv) substrate that can combine the functionality of an antenna / horn as an integral part of its own construction;
v) ability to be manufactured rapidly in an automated assembly facility rather than by hand.
Scientific objectives
1. An enhanced scientific understanding of LNA and diode integration on the same semiconductor wafer. Specifically, the knowledge of achieving a zero-biased or low barrier diode by engineering the semiconductor epilayers and contact processing to effectively shift the square law operating region to a point on the diode IV curve at zero applied DC voltage.
2. An enhanced scientific understanding of GaAs semiconductor wafers using a metamorphic high electron mobility transistor (mHEMT) epilayer instead of pseudomorphic high electron mobility transistors (pHEMT). Specifically, the mHEMT epilayer structure indium electron content should achieve a performance approaching that of the InP HEMT.
3. An enhanced scientific understanding of the material characteristics and flow properties of liquid crystal polymer (LCP) when injection moulded, laser ablated and gold plated, and its signal performance (loss) when used as an antenna and waveguide. Specifically, the effect dielectric constant, loss tangent and coefficient of thermal expansion.
Project results:
The IMAGINE project has been split into several key research and development areas related to: the development of a 94 GHz radiometer chipset; the development of a 94 GHz high-performance, low-cost antenna; the development of high-performance, low-cost substrate material and manufacturing; radiometer integration, assembly and test.
Within these areas of focus, the key results that will enable the EC to benefit most from this research program are:
- the development of processing techniques to enable the design and production of a zero-biased detector diode;
- the development of processing techniques to allow for future MMIC integration of the zero-biased diode with low-noise amplifiers onto a single semiconductor substrate;
- the development of a metallised polymer antenna designed for low cost manufacture.
All of these will drive the advancement of future systems reducing component count, assembly and test costs. However, there are many other results that are exploitable in the nearer term:
- Novel high sensitivity diode epi-layer growth and processing techniques that are compatible with a commercially released mHEMT GaAs process. Thus, allowing the combination of optimum detection and amplification functionality on the same semiconductor substrate.
- Production of a discrete zero-biased, high sensitivity diode.
- Production of a hybrid detector circuit, incorporating the discrete high sensitivity diode.
- Production of a W-band LNA MMIC with excellent noise performance to provide pre-amplification to the hybrid detector circuit.
- Development of multi-layer LCP processing techniques to produce an integrated substrate for housing the semiconductor and power supply electronics.
- Production of a plated, polymer corrugated horn antenna.
- Production of a high performance metal corrugated horn antenna.
These are described in the following sub-sections.
Development platform and requirements
At the outset of the IMAGINE project, it was important to establish a sound platform upon which to base the scientific and technological goals for the project. Work package 1 conducted research to examine the technological needs and specific innovations required to advance current state-of-the-art passive millimetre wave imagers, together with a survey of security imaging applications, in order to identify user and technology requirements that (if satisfied) could enable market growth in this area.
This analysis confirmed that the security concerns of the growing air passenger traffic have highlighted the need to upgrade existing security systems and integrate them with new technology. Screening equipment providers have increased requirements to comply with EU security regulations and standards, whilst at the same time must ensure that their equipment delivers an optimum mix of airport security and passenger convenience.
It was also confirmed that the security industry is making technological advances concerning accuracy and detection but these have drawbacks preventing their widespread adoption. Millimetre wave technology has the potential to transform the airport security screening market in Europe but is more expensive compared to existing screening systems, making it only economically viable for Europe's large airports that have high passenger throughput.
The need for security systems in mass transportation and/or public venues, as well as the need for cost-effective systems that can be used in a wide range and quantity of installations that are small enough to be used in confined spaces, was confirmed also. Systems must be capable of accurately detecting a wide range of dangerous materials, including metallic and non-metallic weapons and explosives (solid and liquid), whilst minimising false alerts. They must be rapid, (walk-by), stand-off, (to prevent bottlenecks or flow restrictions) and have high detection ranges, (to increase warning times).
The market is anticipated to grow in the long term if the above needs can be met, performance is accurate and the expense reduced.
Technologically, the research confirmed that the development of a single semi-conductor wafer containing low noise amplifier (LNA) and detector (diode) would be a clear innovation for passive mm-wave imagers, something not possible previously due to resonance effects and the fact that each device normally requires very different formulations and epilayer structures. Such an achievement would help overcome the problem of separate interconnections, lengthy assembly and testing time.
Furthermore, a novel, optimised semiconductor formulation that exhibits the advantages of both gallium arsenide (GaAs) and indium phosphide (InP) whilst minimising the disadvantages of both would advance current state of the art. Specifically the development of a MMIC module based upon GaAs semiconductor wafer but using a metamorphic high electron mobility transistor (mHEMT) epilayer instead of pseudomorphic high electron mobility transistors (pHEMT) would be considered innovative.
It was also identified that the development of an extremely low cost module and antenna substrate, that does not require lengthy precision engineering from expensive material, would be important. Innovations to injection mould substrates from liquid crystal polymer (LCP), or other suitable thermoplastic materials with an integral antenna and to laser ablate to form waveguides would be extremely beneficial confirming the need for material and manufacturing specialists for feasibility.
A revised set of technical requirements was finally prepared, with consideration to the research findings of work package 1, for a passive mm-wave imager front-end, operating at 94 GHz, for the development of:
i) a radiometer module;
ii) a radiometer chipset that combines a diode, integrated matching circuits and a LNA on the same semiconductor wafer;
iii) a front-end antenna.
The compilation of these requirements successfully concluded work package 1 and provided the technical goals for the following technical work packages in the project.
Development of a 94GHz radiometer chipset
The research and development work concerning the 94 GHz radiometer chipset was performed in the project's work package 2. The objectives were to develop a LNA and a matched zero-biased resonant interband tunnel diode (RITD), to act as a power detector for detecting electromagnetic radiation in the mm-wave range of 75 - 110 GHz. The work involved the development of diode structures and processes compatible with the semiconductor structures and materials processing required for the LNA thus permitting both functions to be integrated onto a single semiconductor substrate. Therefore, the RITD is based on OMMIC's patented epi-layer structure that has the advantage of having the same lattice parameter as the transistors of OMMICs ultra low noise D007IH process and can therefore be integrated with it.
Bare die zero-biased diodes and LNAs, required by the project for work package 5 for the manufacture of the radiometer demonstrators were delivered to the project. The matching between diode and amplifier for the demonstrators was obtained by designing and assembling a hybrid matching circuit on an alumina substrate.
A further goal of the project, combining the diode and LNA on one chip, was very ambitious. The obtained results show that this goal can be achieved, but several difficulties discovered during the work, such as the need to lower diode junction resistance, oscillations of early W-band amplifier designs, proved to be a lot more work than expected delaying progress in this direction.
Nevertheless, even though all goals were not achieved, at the end of the project there exists a broadband mm-wave LNA with state of the art noise performance and a zero-biased diode approaching state of the art performance. This must be considered as a considerable success. On-wafer diode measurement and characterisation shows cut-off frequencies and responsivity corresponding to the required specification. The diodes produced could already compete on the market but still can be further improved for junction resistance and indeed have been improving with each new batch. Once this improvement has reached saturation, it will make sense to grow the combined LNA and RITD epitaxy, and to complete a full integration. This development fits perfectly into the project's exploitation strategy and that of OMMIC who will continue to pursue the opportunity to combine the absolute state of the art performance of its W-band LNA with an integrated diode. This is something that has not yet been realised elsewhere in the world at this time and would be extremely interesting to exploit and demonstrate in an IMAGINE follow-on project.
Zero-biased diode
The first run of the zero-biased diode was characterised and modelled by Chalmers, and provided the feedback that OMMIC required in order to further optimise the diode which was initially identified as having larger values for series and junction resistance (Rs and Rj) than expected. Further optimisation was required and OMMIC performed two further wafer runs to improve the zero-biased diode epitaxy, with respect to Rs and Rj, to develop a zero-biased detector diode approaching state of the art responsivity, assuming correct matching.
Throughout the project, OMMIC designed in total three different mask sets of increasing complexity, including various test structures. Over 200 wafers were fabricated and 78 diode wafer process runs of the successive versions. The masks contained diodes of various anode diameters, and various test structures with different diode diameters both in parallel and series topologies.
The measurement and characterisation results obtained at Chalmers and the in-line results at OMMIC for the zero-biased diode are very similar. The Rj values improved for each wafer run and at the end of the project became an order of magnitude lower than the ones measured earlier in the project for the same diode diameters. On wafer diode low frequency noise measurements were performed on the better diodes from the project's final zero-biased diode wafer run. However, there remains a clear need to lower Rj, and OMMIC will continue to work on lowering Rj values after the project, and expect to reduce Rj by another order of magnitude.
Matched MMIC detector diode
Chalmers made small signal and large signal models, which made the designs of diode matching networks and projections of linearity possible. The extra zero-biased diode wafer runs, required to improve the on-wafer zero-biased RITD performance to the required levels, having a long lead time, meant that a hybrid matched detector diode was designed for flip chip assembly of the best zero-biased diode dies from the project's final zero-biased diode wafer run onto an alumina substrate. This was made together with a matched detector diode design for an integrated matched MMIC detector diode using the OMMIC D007IH process.
Only the version of the alumina substrate was fabricated for the radiometer module demonstrators in work package 5 as the continued diode optimisation research and development meant that the integration with the diode matching circuits was required to wait until the zero-biased diode performance was optimised to a level sufficient for use.
When this was the case there was no time left in the project for the fabrication of the matched detector diode design. Diodes from the final zero biased diode wafer run were thinned to 100 µm, diced and flip-chip assembled onto the hybrid substrate to create the hybrid detector. Five hybrid detectors were assembled and delivered to work package 5.
Once the zero-biased diode improvements reach saturation, the project partners (including OMMIC) hope to exploit this work further with a demonstration action of a complete integrated MMIC detector diode in an IMAGINE follow-on project.
Low noise amplifier (LNA)
Several LNA designs were done initially for the project by MMIC Solutions, using OMMICs D007IH process. There were 4 different designs completed that included 20 circuit variants to mitigate against the uncertainty of the actual device models and process variation. Two completed wafers were delivered which were qualified within process PCM specifications. Some of these designs showed promise but the forced withdrawal of MMIC Solutions due to the SME entering administration during Period 2 of the project meant that this path had to be terminated.
The LNA being a very important part for the performance of the radiometer, the consortium changed strategy. TECS joined the project to replace MMIC Solutions and it was decided to choose OMMICs CGY2190 W-band LNA, based on an original design of Ernesto Limiti (TECS) using the D007IH process. This LNA has been fabricated and measured on wafer and shown to have a bandwidth of 65 - 110 GHz, a mid-band gain of about 25 dB, and state of the art noise performance in W-band (about 2.8 to 3.0 dB over the majority of the band). The power consumption is only 30 mW, well below the 200 mW limit specified for the complete radiometer.
20 CGY2190 LNA bare dies were delivered by OMMIC for the radiometer demonstrators to be assembled and tested in work package 5. These LNAs were assembled and characterised in waveguide modules with promising in-package results showing mid-band gain about 20 dB and NF in the region of 2.8 to 4.0 dB over most of the band. Some stability issues were observed in the lower frequency range < 75 GHz, not surprising as the LNA design is not optimised for a waveguide environment. TECS and OMMIC have continued LNA design optimisation and have a new and improved LNA design recently fabricated and delivered that would be excellent for demonstration and exploitation in a future follow-on project to IMAGINE.
Integration
The ultimate goal is to integrate the diode together with the MMIC detector diode (the zero-biased diode and necessary matching networks) directly on the LNA chip. Chalmers designed the required integrated matching network between the LNA and the detector, using OMMICs design kit for the D007IH process, the same process that is used to build the high performance LNA, for the best zero-biased diodes from the project. Good bandwidth, responsivity and linearity were simulated using the large signal model that was extracted from the on-wafer diode measurements.
OMMIC have designed a mask with the interconnects matching circuits and zero-biased diode, for the integration process that uses a sum of the D007IH process and the discrete diode process. The diode is processed first and then protected for the rest of the chip processing. One extra metal layer is added for interconnect. The transistor parameters are not expected to change with this particular diode technology. If that would be the case, then an integrated solution would not be economical. However, as the zero-biased diode has not reached saturation for its optimisation then no manufacturing cycle has been made as yet. Once the zero biased diode epitaxy and design is final then the integrated matched MMIC detector design can be completed to integrate the detector onto the same chip technology as the LNA. Once again, this would be excellent for demonstration and exploitation in a future follow-on project to IMAGINE.
Antenna design
The objective of work package 3 is to develop a low-cost, high performance antenna that can be integrated with the radiometer chipset developed in work package 2. Antenna gain should be > 20 dBi at 94 GHz. To minimise polarisation loss, a circular horn antenna is developed. To enable integration of the antenna with the MMIC, an antenna feeder and transition to micro-strip is designed that ensures low insertion loss and to preserve stability against manufacturing variations.
A corrugated conical horn antenna for the 94 GHz passive millimetre-wave imaging frequency band was designed specifically with consideration to future integration and industrialisation by injection moulding. A transition to WR-10 waveguide interface was included in the design to provide a suitable measurement interface and to be compatible with existing radiometer modules and imaging systems.
The corrugated horn antenna design was finalised and prototyped as standard metal and polymer versions. The metal antenna provided a performance reference for the corrugated horn antenna design and provided a back-up solution for the polymer antenna as there were many risks that jeopardised the successful manufacture and test of the polymer version. The polymer antenna version (developed in close collaboration with work package 4) provided a successful proof of concept for a potentially low-cost and high performance antenna suitable for manufacture by injection moulding, adaptable for integration into a 94 GHz radiometer front-end. Unfortunately, the quality of the wrought polymer material caused milling difficulties which in turn caused breakage, mechanical defects and metallisation problems with the polymer prototype antenna pieces.
The measured performance of the metal prototype with WR-10 interface shows generally good correlation with simulated performance. It has a measured gain of 22.0 dBi at 94 GHz with side-lobes and cross-polarisation levels below -30 dBc. Measured return loss and gain meet the antenna design requirements over the complete frequency band (75 - 105 GHz). The cross-polarisation for the metal prototype is better than -27 dBc over the complete frequency band.
The measured performance of the polymer antenna prototype shows very promising performance correlating well in most cases with simulations.
Benchmarking of the metal antenna prototype was performed. It almost matched the results achieved by a specific custom designed corrugated horn antenna with considerably larger aperture and improved on results from a commercially available pyramidal and scalar horn antenna having similar apertures. Therefore, the IMAGINE antenna design is suitable for use in an imaging array which was the motivation behind the antenna specification.
Design simulations for the antenna feeder design and transition to micro-strip were completed and met specifications. These were successfully implemented in the LCP PCB demonstrator manufactured in work package 4. Although not directly measurable the results from the LCP demonstrator would indicate insertion loss better than 1dB for the transition and about 0.15 dB/mm for the microstrip.
Deviations from simulated antenna performance are explained by matching measured results with post-simulations and are attributed to prototype manufacturing tolerances. The metal antenna prototype meets the antenna specifications generated from work package 1 indicating that the polymer antenna potentially should meet the design specification. Indeed, the measured results for the polymer antenna prototype are already close to specification at 94 GHz and 105 GHz despite prototype manufacturing issues.
The proof of concept polymer antenna prototype was successful and should be exploited further. Certain foreground IP developed is believed to be novel and work is ongoing to apply for a patent. It is hoped a follow-on IMAGINE project can take place demonstrating the antenna manufactured using prototype injection moulding tooling.
Materials and manufacture
Liquid crystal polymer (LCP) substrate
The objective for the project's work package 4 is to develop an integrated substrate suitable for the manufacture of a low cost MMIC module with excellent thermal and dimensional stability and manufacturing cost. Specifically, the aim was to demonstrate the practical manufacture of an LCP substrate MMIC imaging module having high dimensional stability and accuracy, with focus on substrate and antenna manufacturing, and assembly of the complete module. Materials and processes to suit the specifications from work package 1 were defined. The process was optimised using DfM and DfR methodologies.
Two different LCP PCB build-ups were created and built to specification. The technology using a full LCP build-up and brass metal backing was finally chosen for building the demonstrator due to better manufacturability and electrical performance.
The laser ablation of the chip cavity and adhesion to the corresponding bond pads and the possibility of the ENEPIG plating were demonstrated on the LCP substrate. Wire bonding tests were successful on the LCP substrate.
It would be very interesting to further investigate optimisation of the substrate and its manufacturing costs in a follow-up IMAGINE project. The goals would be to replace chip cavity fabrication by UV laser ablation with CO2 ablation (to decrease process throughput time), to eliminate or replace the back metal brass heat sink with a partly defined back metal heat sink, and, to combine the cost adding high precision and high frequency LCP part with a low cost and low tolerance DC part substrate.
Polymer antenna substrate and metallisation
The objectives were to develop a process for making antenna horns with adequate precision and performance using metallised polymer substrates and to develop the assembly process of the antenna onto the substrate. A thorough analysis of the exact process was carried out once the final design of the horn antenna was complete. The discussion of the manufacturing of the polymer corrugated horn antenna comprised the forming and metallisation processes required for achieving the right functionality of the horn and the choice of methods for large volume manufacturing, as well as rapid prototyping for demonstrating the feasibility of the approach.
It was not possible to perform injection moulding of a polymer based antenna as the costs for manufacturing injection mould tooling were outside the project budget. However, strong collaboration between Acreo and Dyconex resulted in the rapid prototyping of a metalised polymer horn whilst observing the DfM rules established for potential industrialisation. In addition, scoping of the possibilities of manufacturing the horn has been identified together with all relevant partners and third parties.
Standard metallisation processes like galvanic plating and electroless plating were considered as well as physical vapour deposition processes. Machining was used for rapid prototyping the antenna horn and a selection of metallisation methods were tested from the technologies available at Acreo as a proof of concept.
Pieces for the polymer antenna horn demonstrator were manufactured but there were difficulties incurred due to problems making the wrought chosen polymer material. These difficulties caused in turn breakage and defects to many pieces during rapid prototyping as well as metallisation problems. Extra effort was required to solve these problems. Such problems should not exist when injection moulding the chosen polymer in a proper industrialised process. Polymer antenna prototype pieces were finally successfully formed, metallised and assembled that could be subjected to testing in work package 3.
System integration, assembly and testing
The main objective of the project's work package 5 was to test and characterise the fully assembled radiometer module. Two different types of radiometer demonstrator modules were assembled and tested: one using split metal waveguide blocks with the LNA and hybrid detector and zero-biased diode developed in work package 2; one using the LCP PCB demonstrator developed in work package 4 using a commercial chipset.
Integration / assembly of radiometer module
RHe assembled the first prototypes of the 94
GHz single channel radiometer using the low cost high performance LCP substrate manufactured in work package 4. In addition, radiometer modules using the zero-biased diode and LNA designed and manufactured in work package 2 were assembled. In total, five fully functional modules were assembled:
- five test radiometer modules for reference characterisation of LNA chipset;
- two LCP based modules.
For the characterisation of the zero-biased diode, two modules with a single diode flip-chip assembled on to a hybrid and two hybrids with GSG probe-pads were assembled.
Two types of test radiometer modules were produced at RHe, one with a single LNA and one with two cascaded LNAs for additional gain. In respect to the frequency range, very narrow tolerances were specified. A manufacturing flow was created for each of the radiometer modules, the LCP substrate prototypes and the hybrid detector substrates and modules. The challenging part of the assembly was to fit very narrow tolerances for placement and very short wirebonding in order to meet the reference conditions for the chipset mm-wave characterisation. The production flow of the LCP substrate prototype shows clearly the expected improvement of the production flow in order to achieve high performance modules at much reduced cost driving processes.
Testing of radiometer chipset components in-package
Before the final radiometer module was tested, it was important to understand the performance of the individual components, i.e. the LNA and detector, which provide the detecting capability. These components were tested in separate waveguide jigs to understand their isolated performance.
The custom radiometer chipset comprises an LNA and a detector. The LNA circuit, the discrete zero biased diode and their respective RF characteristics are described earlier. A custom hybrid detector, based on the discrete diode, was designed (so that the extra wafer runs required for the zero-biased diode optimisation would not impact work package 5). The hybrid detector consists of the discrete diode flip-chip assembled onto a thin film (alumina) substrate that includes impedance matching structures to achieve the required bandwidth for the detector. This hybrid detector was successfully assembled and is the detector used for radiometer characterisation.
The individual LNA and hybrid detector were packaged in separate split block metal packages. Two variants of the LNA block were packaged, one variant that included a single LNA MMIC and the other that included two LNA MMICs connected in series. The individual blocks for the LNA variants and for the detector have been characterised.
In-package LNA
The LNA has been characterised on-wafer using RF probes to verify the design in work package 2. However, to understand the performance achievable in the application, it is important to characterise the LNA in a package environment where the effects of source and load impedance mismatch and cavity feedback can be seen.
The packaged LNA consists of a split block construction, gold plated aluminium, with WR-10 waveguide interface at the input and output connected to the LNA by input and output quartz thin film RF probes.
The LNAs were tested using two test benches, a noise figure test bench and a vector network analyser test bench.
The NF result is encouraging and demonstrates the low noise capability of the OMMIC D007IH process and the low noise design of the LNA. This result is state of the art for GaAs based substrates and comparable to the NF that can be achieved on more exotic and expensive InP processes. The NF of the LNA and the packaging is one of the key figures of merit for a radiometer and a determinant of the overall system noise and therefore detection capability.
The gain of the LNA with frequency is broadband, covering 70 - 100 GHz. For a passive radiometer, a general design rule is to have as wide a bandwidth as possible to improve the signal to noise ratio and therefore detection. Also, a certain amount of gain is required prior to the detection to raise the signal level above the noise floor of the detector. Two of the single LNAs cascaded together would provide sufficient gain to achieve this. Some problems were experienced with the stability of the LNA when biased for high gain and assembled in the waveguide modules. A selection of damping lid alternatives was fabricated to improve stability and measurement results.
In-package hybrid detector
The hybrid detector was packaged in a split block metal package, similar to the LNAs. The input to the detector is an RF signal and the output is a DC signal.
The test set-up consists of a mm-wave signal source to provide power over the frequency range 75 - 110 GHz and a voltmeter to measure the output voltage. A synthesiser is multiplied to the required frequency, then the signal is passed through a variable waveguide attenuator to set the input power at the detector input. The power level at the detector input is calibrated using a spectrum analyser.
The LCP substrate-based radiometer modules were assembled using the chipset from HRL. During characterisation of this receiver, there were problems encountered thought to be due to stability issues of the package interacting with the chipset. One of the receivers that was produced was damaged due to this problem. The RF components used in the front end have relatively small breakdown voltages. If an oscillation builds up the signal level can damage the actual semiconductor devices.
The second LCP substrate-based radiometer did function and was able to detect small changes in the input temperature. The thermal sensitivity is referenced to the output of the detector and was measured to be about 2.2 µV/K which is in the expected range for the module and would normally yield a receiver with NETD < 1.0K in accordance with the target specification for the passive mm-wave radiometer. However, the output DC voltage level was higher than expected.
To summarise, bench testing of the manufactured and assembled integrated radiometer modules, based on the Dyconex LCP substrate, was completed showed promising results, even though there were a few issues seen during the testing. Testing of the separately packaged 94 GHz radiometer chipset from work package 2 (W-band LNA and hybrid detector circuit with the zero-biased diode) for passive imaging has been completed also. The LNA achieves state of the art noise figure performance, is broadband and achieves sufficient gain for two LNAs to be cascaded together for the required level of pre-amplification prior to the hybrid detector. The hybrid detector achieves broadband matching. However, its responsivity in-package is lower than expected. More investigation is required after the project to understand why. Testing of a complete radiometer incorporating the 94 GHz radiometer chipset from work package 2 has been performed but is not yet completed due to slippage in the schedule.
Performance validation
As described previously, two radiometer modules have been developed in this project. One demonstrates the use of an LCP substrate, the other demonstrates the zero-biased diode and LNA. The performance validation evaluates the radiometer module performance in the system and compares it with the bench characterisation results for noise figure and NETD, in addition to comparing the imaging results with those obtained with the incumbent radiometer.
The demonstrator imaging system, property of GATE S.A. is used to test receivers before integrating them in their imaging product.
The imager has an opto-mechanical scanning system that does not use any frequency selective components and can therefore operate with different frequency receivers, as well as having a theoretical 100 % transmission. It has been designed to work as a passive system. This system has been designed to have a 6 mrad spatial resolution.
The system uses a combination of rotating mirrors to produce a high speed linear scan pattern of ±10 º in the vertical plane. This configuration is combined with a plane flapping mirror that flaps to scan 60 º horizontally in the scene. In this way only one receiver is needed.
A mounting fixture was prepared to assemble the radiometer modules into the GATE demonstrator imaging system. The power supply and acquisition electronics were also adapted and modified for the LCP substrate and waveguide-based radiometer modules. The mounting fixture was designed to also accommodate the reference GATE single pixel receiver. The three radiometer module types are to be tested with the standard pyramidal horn antenna, as seen in the above figures, for comparison purposes.
To ensure that the system operates correctly within the limits set in the technical requirements from work package 1, the IMAGINE radiometers were to be installed in the imaging system and passive images of real subjects hiding objects under their clothing were to be taken. The detection rate was to be compared with the incumbent radiometer solution.
The demonstrator system user interface has been programmed to show the raw mm-wave image next to the automatic threat detection image for the two IMAGINE receivers plus the reference GATE single pixel receiver. The subjective image quality will be compared between the three radiometers, in addition to the detection rates provided by the automatic threat detection algorithm.
Unfortunately, during the in-system performance tests of the LCP radiometer module, the module started to behave incorrectly. After investigation, it was discovered that the LNA in the module was damaged and no signal output was produced by the module.
It will be investigated why this has happened, as the demonstration and validation of this module is of great importance to the project partners and their everyday business, however this will now have to be done outside of the IMAGINE project as there was no time to do this before the project final review. Once able to make the tests, the in-system NETD and NF will be compared to those obtained with the reference GATE single pixel receiver.
The in-system performance and scanner tests were not able to be done on the IMAGINE radiometer module, as lower than expected responsivity was measured for this during characterisation, and further work needs to be done before this validation can take place.
Potential impact:
There have been many results produced in IMAGINE. Some results are exploitable in the short term and therefore can have an impact sooner, for example the development of specific semiconductor products. Some results provide a building block for future work and therefore can be exploited over a longer timeframe, as the technology is demonstrated more. The key results, their use and impact are discussed below.
The key development work carried out in IMAGINE has been centred on the development of the IC front end for passive imaging. As a result of this, IMAGINE has established an EU source (OMMIC) for state-of-the-art semiconductor processing and manufacture capable of supplying chipsets for passive mm-wave imaging applications. OMMIC, building on its background IP in semiconductor capability, has developed novel high sensitivity diode epi-layer growth and processing techniques that are compatible with its commercially released mHEMT GaAs process. This capability will allow the combination of optimum detection and amplification functionality on the same semiconductor substrate, a key enabler toward a low cost passive mm-wave solution.
Prior to IMAGINE, companies interested in generating business from passive mm-wave applications had to rely on wholly sourced US semiconductor parts, that were expensive and at risk of US export regulations. Both of these factors put financial pressure, uncertainty and risk on the operations of EU companies to supply the necessary components for mm-wave markets. Now that IMAGINE has established an EU source for mm-wave semiconductor processing, these risks and issues can be countered and allow EU companies to develop parts for passive imaging markets that are price competitive and secure of supply.
Although a product has not been manufactured that incorporates a detector and LNA on the same semiconductor substrate, the process is in place to do this and the capability will be demonstrated once the diode has a suitable junction resistance (< 10 k?). The impact of having an EU semiconductor source with this capability is that the building blocks are in place for the technology to be exploited not only by consortium members but by other companies. This widens the reach of the advantages gained from IMAGINE. For example, OMMIC will incorporate the developed diode into its standard design libraries and offer these to 3rd party MMIC design companies to design products using its newly developed process. The impact of this will be felt over the medium to longer term (3 - 5 yrs). The third party EU companies will gain as now they have access to state-of-the-art processing that was not previously available. OMMIC will gain from increased revenue, throughput and production learning. The companies in IMAGINE will benefit from preferential pricing and access, and also as now there is a wider design pool, potentially developing more advanced products and with more throughput, the processing costs should be reduced, resulting in a lower cost product.
Opening up the access to these semiconductor processes will result in products for other applications being developed, as designers exploit the technology developed within IMAGINE. As an example of this, we could consider the design of frequency mixers and modulators for next generation communications systems and radar applications.
As well as the baseline semiconductor processing development, several prototype products have also been designed, optimised and manufactured. These include a discrete diode, a hybrid detector (using the discrete diode) and a discrete LNA MMIC. The impact of this is already being seen in the short term as OMMIC have the LNA as a standard catalogue part for general sale.
The development of the hybrid detector was a key step in the product development of the final MMIC detector circuit, which has been designed but unfortunately will not be manufactured in time for completion of the project. However, in the short term the impact of the hybrid detector will be to provide the consortium with an interim detector part for further prototyping. RHe manufacture and assemble the detector, so there will be a positive financial impact to them and OMMIC provide the discrete diode. GATE can use the LNA and hybrid detector to build several sample systems.
IMAGINE also focused on package and antenna development. A key result from WP4 was the development of LCP processing techniques to manufacture an integrated radiometer design where the antenna feed transition (WP3), RF and DC electronics are located on the same substrate. In addition to this, an antenna was developed, based on design rules for injection moulding, which was manufactured from LCP and then metalised. The metalised LCP antenna achieved encouraging results when compared to its metal machined counterpart.
Both of these results provide a sound technology platform for improving the integration of passive imaging receiver front ends and therefore will impact the cost of passive imaging systems. Also, in the future, this technology platform will allow the development of different receiver architectures and therefore also possibly different types of passive imaging systems. For example, smaller form factor, starring array and hand held type devices.
The integration of more functionality at the component level is seen as key to reducing sub-system and general system assembly and test costs, which can be a significant part (50 %) of the overall system cost. Therefore, integrating more at the module level and having an antenna technology that is compatible with the module would lead to lower system costs, improving operating margins and potentially sales growth in a positive way. This in turn would benefit the supply chain within the consortium as the supplier at each different level would benefit from increased revenue.
As well as a direct positive financial impact to the consortium members involved in the supply chain, Dyconex and RHe have also benefited from improving their knowhow of mm-wave processing, manufacturing and assembly techniques and increasing their IP related to these areas. Therefore, they are in a stronger position, as a result of IMAGINE, to offer similar manufacturing services to other potential customers. The impact of this will be seen by other companies who can now access these improved mm-wave manufacturing services and develop more competitive products for their markets.
A limiting factor of current systems is the size and necessary orientation of receivers to fit within the specified optics and scanning mechanisms. With increased levels of integration at the receiver level and lower cost, theoretically more receivers could be packaged together to improve overall system performance without increasing the overall system cost. These new system architectures could result in a migration from scanning system architectures to using different focusing lenses and more 'starring' arrays. This would impact the safety of EU citizens as there would be different types of security systems available for their protection.
The consortium for IMAGINE was established to include the whole supply chain required to produce a mm-wave imaging receiver. The supply chain includes; semiconductor processing (OMMIC), design (TECS, CUT, ACREO), substrate supplier (Rogers), substrate manufacture (Dyconex) and assembly and test (RHe). An impact of the program is that the consortium now has experience of working together and understands the difficulties and challenges of producing a mm-wave receiver. Therefore, an outcome of IMAGINE is that the consortium / supply chain is better placed to make a success of the technology developed.
In summary, the developments at both the semiconductor level and the package level could provide a paradigm shift in terms of the approach to mm-wave imaging receiver design and manufacture. Further work, mainly optimisation for production, is necessary for this to happen (a demonstration action proposal will be submitted for this, as this is in-line with the relevant project partners' current and future business objectives). This in turn could lead to different system architectures that not only service current applications (portal imaging) but also open up new application areas (concealed stand-off, hand held detection) that are more competitive in terms of cost, yet also maintain the required performance metrics.
Socioeconomic impact
Passive imaging technology effectively allows detection of concealed objects beneath clothing. Therefore, one of the main applications of the technology is for security and safety and this is where the biggest social impact will be felt. There are three main security application areas:
1) transport hubs - airports and rail and bus stations;
2) critical infrastructure buildings - court houses, financial centres, museums and other public buildings; and
3) large public events, for example sport and music events.
With the adoption and deployment of passive imaging technology at the centres mentioned above, the levels of security will be improved. This will have an impact to society in creating a greater sense of safety and well-being, resulting in more people travelling and attending events thus also having a positive outcome on the wider economy.
Modern day security measures often rely on police or other government agency presence. With the adoption of passive imaging systems, the amount of person presence at the locations / events described above could be reduced. This would have a knock on impact of reducing the required government security budgets to support transport operations or public events, which would be of benefit to the tax payer. In another scenario, the resources could be redeployed in other public service areas to the greater good of society.
Another application area of passive imaging is in theft prevention. As the technology can effectively 'see' beneath clothing, it can be used as a deterrent for theft prevention. In retail outlets and distribution centres, shoppers and workers alike would be deterred from stealing high value small form factor goods. This would reduce the amount of contraband available on the underground market and reduce the associated costs that companies assign to theft. Therefore companies operating margins would increase, benefitting shareholders and the wider society in general.
In terms of direct economic benefits, there is huge potential for wealth to be created. The market for passive imaging is relatively immature and so has huge potential to grow. With the development of passive imaging technology from IMAGINE, there exists the opportunity for job creation to support the supply chain delivering the necessary products into this market. These jobs all require relatively high skilled labour, so there will be a general increase in the levels of capability, knowledge and IP across the labour force working in this area. Up-skilling the labour force in this way will have a positive impact in terms of worker opportunities, salaries earned and therefore levels of taxes paid that can be reinvested by the government to the greater good of society.
Wider societal implications
In terms of wider societal implications we refer to indirect impacts of the technology to society.
As the market grows for passive imaging, other application areas will emerge to use the technology. These opportunities will either be directly able to redeploy the technology or build on the technological base provided by IMAGINE. In either case, these opportunities will foster further investment, technology development, up-skill in labour, job creation and wealth creation for the wider society.
There could be certain applications of the technology in military environments. These include using the technology as a landing aid in hazardous environmental conditions and using it for people screening at military checkpoints. In these applications, the technology saves the costs associated with damaging expensive equipment, but more importantly saves lives.
Main dissemination activities and exploitation of results
One of the main dissemination activities that has taken place is the publication and maintenance of the project website. It allows the project background, beneficiaries and any non-confidential project results to be freely disseminated to the public. The home page currently presents a general introduction to the IMAGINE project. Contact details and EC funding details are clearly identified on each webpage. The members' area contains folders where confidential project documents are stored and shared between the consortium such as deliverables, meeting minutes, presentations and the consortium agreement.
Several project presentations have been given at seminars and meetings across Europe and a project poster in A0 format has also been created and presented. Further conference presentations are scheduled throughout this year and next.
Customer specific marketing and product launches will take place, once the project results have been optimised and reached a more production-ready state. The project partners are committed to this work, which forms part of their individual business plans, and a demonstration activity will also be presented to pursue this.
An exploitation plan has been prepared which establishes the exploitation and supply chain for each foreground IP developed in the project. Private licensing agreements have been put in place to cover collaborations between the partners to fully facilitate exploitation of the foreground technology. These encompass agreements in respect to the protection of intellectual property, and go on to detail the terms and conditions under which licensing of the technology can take place. This licensing to third parties is seen as critical to the rapid roll out of the technology across the European Union and beyond, speeding the proliferation of the technology and penetration of different market sectors and foreign markets.
In the IMAGINE project, licensing rights refer to the granting of licences to partners within the project consortium at fair and reasonable rates. They are granted to partners who have no direct input to a project result but wish to market the result as a desirable component of their own products in a non-competing market. This preferential access is granted at affordable rates that reflect the collaborative nature of this project where all partners have made at least indirect contributions to the entire technology. Following this principle, three royalty levels have been established:
- 'reduced' = 2 % for the SME partners, for the project results they have paid for;
- 'reasonable' = 5 % for any other project partners;
- 'market' = 10 % for anyone outside the project.
Agreements to supply systems or components or material between the SME partners and the large enterprise partners as a result of the work carried out in this project are restricted in nature (i.e. preclude the future supply to/from other users and material suppliers). The supply chains described in the Exploitation Plan are based on a preferential pricing for consortium members policy, and although the first choice is to maintain these supply chains and importance is given to them being exclusively European, they are not binding.
The process of patenting the antenna and front-end integration concept has also been launched.
The project public website address is:
http://www.acreo.se/IMAGINE
The contact details for the project coordinator (SME partner) are:
Gestión Avanzada de Tecnologías Electrónicas, GATE S.A.
Francisco Pérez-Villacastín
fpvillacastin@gatesa.com
Tel: +34-915-159416
The contact details for the technical project manager (RTD partner) are:
Acreo AB
Duncan Platt
duncan.platt@acreo.se
Tel: +46-863-27854
The contact details for the SME project partners are:
Dyconex AG
Daniel Schulze
daniel.schulze@mst.com
Tel.: +41-432-661169
TECS - Technological Consulting Services s.r.l.
Ernesto Limiti
limiti@ing.uniroma2.it
Tel.: +39-067-2597953
The contact details for the RTD project partners are:
Ommic SAS
Peter Frijlink
p.frijlink@ommic.com
Tel.: +33-(0)14-5106731
Chalmers Tekniska Hoegskola AB
Vessen Vassilev
vessen.vassilev@chalmers.se
Tel: +46-317-721894
The contact details for the other project partners are:
RHe Microsystems GmbH
Sebastian Löffler
sebastian.loeffler@rhe.de
Tel.: +49-352-8419924
Rogers BVBA
John Hendricks
john.hendricks@rogerscorporation.com
Tel.: +32-923-53310
Protecting its citizens from terrorism is a high priority for the EC. Current state of the art security procedures for air travel have significantly improved airport security. The need is now to protect the softer, unprotected areas such as mass transportation systems and hubs that could be targeted with devastating effect (as was the case in the terrible attacks in e.g. London and Madrid). Such areas are largely unprotected because current security systems are very expensive, bulky and too slow.
Therefore, there is an urgent need for innovative new security screening technology that can provide low cost, high performance, rapid 'walk-by' screening at normal flow rates.
Whilst mm-wave technology is the leading technology, cost is a barrier. The critical part of such systems is the detector module; at a cost of over EUR 1000 per pixel, the imager module accounts for 60 % of the overall system cost. This high cost is due to the cost of semiconductor material and the cost of assembly and tuning to overcome resonance effects.
The IMAGINE project aimed therefore to perform research and development of innovative solutions to increase integration, reduce size and costs, whilst maintaining high performance, for passive mm-wave imager front-end modules which would allow this technology to be deployed for security applications within an increased range of critical locations across Europe.
The project coordinator was GATE S.A. and the project technical coordinator was Acreo.
The block diagram of the passive mm-wave imager front-end module developed for a single pixel is shown below. The main innovation areas for the project were: development of a zero-biased detector diode; development of a low noise amplifier (LNA); MMIC integration of the zero-biased diode and LNA; development of a compact high performance broadband mm-wave antenna; integration of the front-end components into a compact, low cost module based on a high performance LCP carrier.
The project developed a demonstrator that was tested during the final stages of the project in one of GATE's passive mm-wave imaging systems.
This was an extremely challenging project requiring significant scientific knowledge generation and technology development. The SMEs involved did not have all the in-house skills to develop this solution alone and the skill gaps were provided by the RTD performers. The US currently dominates the growing imaging market (USD 49 million, predicted to grow by 1800 % in 5 years) which we aim to access for Europe with this project. Without the research for SME initiative, the SMEs would not have had the financial resources to engage this leading European expertise.
Project context and objectives:
Protecting its citizens from terrorism remains a high priority for the EC. Current SOA security procedures for air travel have significantly improved airport security. The need is now to protect the softer, unprotected areas such as mass transportation systems and hubs which are being targeted with devastating effect. They are largely unprotected since current security systems are too expensive and too slow. Therefore, there is an urgent need for innovative new security screening technology that can provide a low cost, rapid 'walk-by' screening at normal flow rates. Whilst millimetre-wave (mm-wave) technology is the leading technology, cost is a barrier. The critical part of mm-wave systems is the detector module; at a cost of EUR 1125 per pixel the module accounts for 60 % of the overall system cost. At present, this high cost is due to the cost of semiconductor material and the cost of assembly and tuning to overcome resonance effects.
In order for mm-wave imager systems to become competitive for mass transit applications we need to reduce dramatically the cost of the mm-wave detector modules down to around EUR 150 retail price. Lower cost modules will not only enable more scanners to be introduced but will allow a greater number of pixels per scanner, reducing throughput times dramatically. This is clearly an extremely ambitious target and in order to achieve this we will clearly need to overcome all of the aforementioned reasons for high cost. Such a unit will need to have the following characteristics:
i) single semi-conductor wafer containing the low noise amplifier (LNA) and detector (diode). This will overcome the problem of separate interconnections, lengthy assembly and testing time;
ii) optimised semiconductor formulation that exhibits the advantages of both gallium arsenide (GaAs) and indium phosphide (InP) whilst minimising the disadvantages of both;
iii) extremely low cost substrate that does not require lengthy precision engineering from expensive materials;
iv) substrate that can combine the functionality of an antenna / horn as an integral part of its own construction;
v) ability to be manufactured rapidly in an automated assembly facility rather than by hand.
Scientific objectives
1. An enhanced scientific understanding of LNA and diode integration on the same semiconductor wafer. Specifically, the knowledge of achieving a zero-biased or low barrier diode by engineering the semiconductor epilayers and contact processing to effectively shift the square law operating region to a point on the diode IV curve at zero applied DC voltage.
2. An enhanced scientific understanding of GaAs semiconductor wafers using a metamorphic high electron mobility transistor (mHEMT) epilayer instead of pseudomorphic high electron mobility transistors (pHEMT). Specifically, the mHEMT epilayer structure indium electron content should achieve a performance approaching that of the InP HEMT.
3. An enhanced scientific understanding of the material characteristics and flow properties of liquid crystal polymer (LCP) when injection moulded, laser ablated and gold plated, and its signal performance (loss) when used as an antenna and waveguide. Specifically, the effect dielectric constant, loss tangent and coefficient of thermal expansion.
Project results:
The IMAGINE project has been split into several key research and development areas related to: the development of a 94 GHz radiometer chipset; the development of a 94 GHz high-performance, low-cost antenna; the development of high-performance, low-cost substrate material and manufacturing; radiometer integration, assembly and test.
Within these areas of focus, the key results that will enable the EC to benefit most from this research program are:
- the development of processing techniques to enable the design and production of a zero-biased detector diode;
- the development of processing techniques to allow for future MMIC integration of the zero-biased diode with low-noise amplifiers onto a single semiconductor substrate;
- the development of a metallised polymer antenna designed for low cost manufacture.
All of these will drive the advancement of future systems reducing component count, assembly and test costs. However, there are many other results that are exploitable in the nearer term:
- Novel high sensitivity diode epi-layer growth and processing techniques that are compatible with a commercially released mHEMT GaAs process. Thus, allowing the combination of optimum detection and amplification functionality on the same semiconductor substrate.
- Production of a discrete zero-biased, high sensitivity diode.
- Production of a hybrid detector circuit, incorporating the discrete high sensitivity diode.
- Production of a W-band LNA MMIC with excellent noise performance to provide pre-amplification to the hybrid detector circuit.
- Development of multi-layer LCP processing techniques to produce an integrated substrate for housing the semiconductor and power supply electronics.
- Production of a plated, polymer corrugated horn antenna.
- Production of a high performance metal corrugated horn antenna.
These are described in the following sub-sections.
Development platform and requirements
At the outset of the IMAGINE project, it was important to establish a sound platform upon which to base the scientific and technological goals for the project. Work package 1 conducted research to examine the technological needs and specific innovations required to advance current state-of-the-art passive millimetre wave imagers, together with a survey of security imaging applications, in order to identify user and technology requirements that (if satisfied) could enable market growth in this area.
This analysis confirmed that the security concerns of the growing air passenger traffic have highlighted the need to upgrade existing security systems and integrate them with new technology. Screening equipment providers have increased requirements to comply with EU security regulations and standards, whilst at the same time must ensure that their equipment delivers an optimum mix of airport security and passenger convenience.
It was also confirmed that the security industry is making technological advances concerning accuracy and detection but these have drawbacks preventing their widespread adoption. Millimetre wave technology has the potential to transform the airport security screening market in Europe but is more expensive compared to existing screening systems, making it only economically viable for Europe's large airports that have high passenger throughput.
The need for security systems in mass transportation and/or public venues, as well as the need for cost-effective systems that can be used in a wide range and quantity of installations that are small enough to be used in confined spaces, was confirmed also. Systems must be capable of accurately detecting a wide range of dangerous materials, including metallic and non-metallic weapons and explosives (solid and liquid), whilst minimising false alerts. They must be rapid, (walk-by), stand-off, (to prevent bottlenecks or flow restrictions) and have high detection ranges, (to increase warning times).
The market is anticipated to grow in the long term if the above needs can be met, performance is accurate and the expense reduced.
Technologically, the research confirmed that the development of a single semi-conductor wafer containing low noise amplifier (LNA) and detector (diode) would be a clear innovation for passive mm-wave imagers, something not possible previously due to resonance effects and the fact that each device normally requires very different formulations and epilayer structures. Such an achievement would help overcome the problem of separate interconnections, lengthy assembly and testing time.
Furthermore, a novel, optimised semiconductor formulation that exhibits the advantages of both gallium arsenide (GaAs) and indium phosphide (InP) whilst minimising the disadvantages of both would advance current state of the art. Specifically the development of a MMIC module based upon GaAs semiconductor wafer but using a metamorphic high electron mobility transistor (mHEMT) epilayer instead of pseudomorphic high electron mobility transistors (pHEMT) would be considered innovative.
It was also identified that the development of an extremely low cost module and antenna substrate, that does not require lengthy precision engineering from expensive material, would be important. Innovations to injection mould substrates from liquid crystal polymer (LCP), or other suitable thermoplastic materials with an integral antenna and to laser ablate to form waveguides would be extremely beneficial confirming the need for material and manufacturing specialists for feasibility.
A revised set of technical requirements was finally prepared, with consideration to the research findings of work package 1, for a passive mm-wave imager front-end, operating at 94 GHz, for the development of:
i) a radiometer module;
ii) a radiometer chipset that combines a diode, integrated matching circuits and a LNA on the same semiconductor wafer;
iii) a front-end antenna.
The compilation of these requirements successfully concluded work package 1 and provided the technical goals for the following technical work packages in the project.
Development of a 94GHz radiometer chipset
The research and development work concerning the 94 GHz radiometer chipset was performed in the project's work package 2. The objectives were to develop a LNA and a matched zero-biased resonant interband tunnel diode (RITD), to act as a power detector for detecting electromagnetic radiation in the mm-wave range of 75 - 110 GHz. The work involved the development of diode structures and processes compatible with the semiconductor structures and materials processing required for the LNA thus permitting both functions to be integrated onto a single semiconductor substrate. Therefore, the RITD is based on OMMIC's patented epi-layer structure that has the advantage of having the same lattice parameter as the transistors of OMMICs ultra low noise D007IH process and can therefore be integrated with it.
Bare die zero-biased diodes and LNAs, required by the project for work package 5 for the manufacture of the radiometer demonstrators were delivered to the project. The matching between diode and amplifier for the demonstrators was obtained by designing and assembling a hybrid matching circuit on an alumina substrate.
A further goal of the project, combining the diode and LNA on one chip, was very ambitious. The obtained results show that this goal can be achieved, but several difficulties discovered during the work, such as the need to lower diode junction resistance, oscillations of early W-band amplifier designs, proved to be a lot more work than expected delaying progress in this direction.
Nevertheless, even though all goals were not achieved, at the end of the project there exists a broadband mm-wave LNA with state of the art noise performance and a zero-biased diode approaching state of the art performance. This must be considered as a considerable success. On-wafer diode measurement and characterisation shows cut-off frequencies and responsivity corresponding to the required specification. The diodes produced could already compete on the market but still can be further improved for junction resistance and indeed have been improving with each new batch. Once this improvement has reached saturation, it will make sense to grow the combined LNA and RITD epitaxy, and to complete a full integration. This development fits perfectly into the project's exploitation strategy and that of OMMIC who will continue to pursue the opportunity to combine the absolute state of the art performance of its W-band LNA with an integrated diode. This is something that has not yet been realised elsewhere in the world at this time and would be extremely interesting to exploit and demonstrate in an IMAGINE follow-on project.
Zero-biased diode
The first run of the zero-biased diode was characterised and modelled by Chalmers, and provided the feedback that OMMIC required in order to further optimise the diode which was initially identified as having larger values for series and junction resistance (Rs and Rj) than expected. Further optimisation was required and OMMIC performed two further wafer runs to improve the zero-biased diode epitaxy, with respect to Rs and Rj, to develop a zero-biased detector diode approaching state of the art responsivity, assuming correct matching.
Throughout the project, OMMIC designed in total three different mask sets of increasing complexity, including various test structures. Over 200 wafers were fabricated and 78 diode wafer process runs of the successive versions. The masks contained diodes of various anode diameters, and various test structures with different diode diameters both in parallel and series topologies.
The measurement and characterisation results obtained at Chalmers and the in-line results at OMMIC for the zero-biased diode are very similar. The Rj values improved for each wafer run and at the end of the project became an order of magnitude lower than the ones measured earlier in the project for the same diode diameters. On wafer diode low frequency noise measurements were performed on the better diodes from the project's final zero-biased diode wafer run. However, there remains a clear need to lower Rj, and OMMIC will continue to work on lowering Rj values after the project, and expect to reduce Rj by another order of magnitude.
Matched MMIC detector diode
Chalmers made small signal and large signal models, which made the designs of diode matching networks and projections of linearity possible. The extra zero-biased diode wafer runs, required to improve the on-wafer zero-biased RITD performance to the required levels, having a long lead time, meant that a hybrid matched detector diode was designed for flip chip assembly of the best zero-biased diode dies from the project's final zero-biased diode wafer run onto an alumina substrate. This was made together with a matched detector diode design for an integrated matched MMIC detector diode using the OMMIC D007IH process.
Only the version of the alumina substrate was fabricated for the radiometer module demonstrators in work package 5 as the continued diode optimisation research and development meant that the integration with the diode matching circuits was required to wait until the zero-biased diode performance was optimised to a level sufficient for use.
When this was the case there was no time left in the project for the fabrication of the matched detector diode design. Diodes from the final zero biased diode wafer run were thinned to 100 µm, diced and flip-chip assembled onto the hybrid substrate to create the hybrid detector. Five hybrid detectors were assembled and delivered to work package 5.
Once the zero-biased diode improvements reach saturation, the project partners (including OMMIC) hope to exploit this work further with a demonstration action of a complete integrated MMIC detector diode in an IMAGINE follow-on project.
Low noise amplifier (LNA)
Several LNA designs were done initially for the project by MMIC Solutions, using OMMICs D007IH process. There were 4 different designs completed that included 20 circuit variants to mitigate against the uncertainty of the actual device models and process variation. Two completed wafers were delivered which were qualified within process PCM specifications. Some of these designs showed promise but the forced withdrawal of MMIC Solutions due to the SME entering administration during Period 2 of the project meant that this path had to be terminated.
The LNA being a very important part for the performance of the radiometer, the consortium changed strategy. TECS joined the project to replace MMIC Solutions and it was decided to choose OMMICs CGY2190 W-band LNA, based on an original design of Ernesto Limiti (TECS) using the D007IH process. This LNA has been fabricated and measured on wafer and shown to have a bandwidth of 65 - 110 GHz, a mid-band gain of about 25 dB, and state of the art noise performance in W-band (about 2.8 to 3.0 dB over the majority of the band). The power consumption is only 30 mW, well below the 200 mW limit specified for the complete radiometer.
20 CGY2190 LNA bare dies were delivered by OMMIC for the radiometer demonstrators to be assembled and tested in work package 5. These LNAs were assembled and characterised in waveguide modules with promising in-package results showing mid-band gain about 20 dB and NF in the region of 2.8 to 4.0 dB over most of the band. Some stability issues were observed in the lower frequency range < 75 GHz, not surprising as the LNA design is not optimised for a waveguide environment. TECS and OMMIC have continued LNA design optimisation and have a new and improved LNA design recently fabricated and delivered that would be excellent for demonstration and exploitation in a future follow-on project to IMAGINE.
Integration
The ultimate goal is to integrate the diode together with the MMIC detector diode (the zero-biased diode and necessary matching networks) directly on the LNA chip. Chalmers designed the required integrated matching network between the LNA and the detector, using OMMICs design kit for the D007IH process, the same process that is used to build the high performance LNA, for the best zero-biased diodes from the project. Good bandwidth, responsivity and linearity were simulated using the large signal model that was extracted from the on-wafer diode measurements.
OMMIC have designed a mask with the interconnects matching circuits and zero-biased diode, for the integration process that uses a sum of the D007IH process and the discrete diode process. The diode is processed first and then protected for the rest of the chip processing. One extra metal layer is added for interconnect. The transistor parameters are not expected to change with this particular diode technology. If that would be the case, then an integrated solution would not be economical. However, as the zero-biased diode has not reached saturation for its optimisation then no manufacturing cycle has been made as yet. Once the zero biased diode epitaxy and design is final then the integrated matched MMIC detector design can be completed to integrate the detector onto the same chip technology as the LNA. Once again, this would be excellent for demonstration and exploitation in a future follow-on project to IMAGINE.
Antenna design
The objective of work package 3 is to develop a low-cost, high performance antenna that can be integrated with the radiometer chipset developed in work package 2. Antenna gain should be > 20 dBi at 94 GHz. To minimise polarisation loss, a circular horn antenna is developed. To enable integration of the antenna with the MMIC, an antenna feeder and transition to micro-strip is designed that ensures low insertion loss and to preserve stability against manufacturing variations.
A corrugated conical horn antenna for the 94 GHz passive millimetre-wave imaging frequency band was designed specifically with consideration to future integration and industrialisation by injection moulding. A transition to WR-10 waveguide interface was included in the design to provide a suitable measurement interface and to be compatible with existing radiometer modules and imaging systems.
The corrugated horn antenna design was finalised and prototyped as standard metal and polymer versions. The metal antenna provided a performance reference for the corrugated horn antenna design and provided a back-up solution for the polymer antenna as there were many risks that jeopardised the successful manufacture and test of the polymer version. The polymer antenna version (developed in close collaboration with work package 4) provided a successful proof of concept for a potentially low-cost and high performance antenna suitable for manufacture by injection moulding, adaptable for integration into a 94 GHz radiometer front-end. Unfortunately, the quality of the wrought polymer material caused milling difficulties which in turn caused breakage, mechanical defects and metallisation problems with the polymer prototype antenna pieces.
The measured performance of the metal prototype with WR-10 interface shows generally good correlation with simulated performance. It has a measured gain of 22.0 dBi at 94 GHz with side-lobes and cross-polarisation levels below -30 dBc. Measured return loss and gain meet the antenna design requirements over the complete frequency band (75 - 105 GHz). The cross-polarisation for the metal prototype is better than -27 dBc over the complete frequency band.
The measured performance of the polymer antenna prototype shows very promising performance correlating well in most cases with simulations.
Benchmarking of the metal antenna prototype was performed. It almost matched the results achieved by a specific custom designed corrugated horn antenna with considerably larger aperture and improved on results from a commercially available pyramidal and scalar horn antenna having similar apertures. Therefore, the IMAGINE antenna design is suitable for use in an imaging array which was the motivation behind the antenna specification.
Design simulations for the antenna feeder design and transition to micro-strip were completed and met specifications. These were successfully implemented in the LCP PCB demonstrator manufactured in work package 4. Although not directly measurable the results from the LCP demonstrator would indicate insertion loss better than 1dB for the transition and about 0.15 dB/mm for the microstrip.
Deviations from simulated antenna performance are explained by matching measured results with post-simulations and are attributed to prototype manufacturing tolerances. The metal antenna prototype meets the antenna specifications generated from work package 1 indicating that the polymer antenna potentially should meet the design specification. Indeed, the measured results for the polymer antenna prototype are already close to specification at 94 GHz and 105 GHz despite prototype manufacturing issues.
The proof of concept polymer antenna prototype was successful and should be exploited further. Certain foreground IP developed is believed to be novel and work is ongoing to apply for a patent. It is hoped a follow-on IMAGINE project can take place demonstrating the antenna manufactured using prototype injection moulding tooling.
Materials and manufacture
Liquid crystal polymer (LCP) substrate
The objective for the project's work package 4 is to develop an integrated substrate suitable for the manufacture of a low cost MMIC module with excellent thermal and dimensional stability and manufacturing cost. Specifically, the aim was to demonstrate the practical manufacture of an LCP substrate MMIC imaging module having high dimensional stability and accuracy, with focus on substrate and antenna manufacturing, and assembly of the complete module. Materials and processes to suit the specifications from work package 1 were defined. The process was optimised using DfM and DfR methodologies.
Two different LCP PCB build-ups were created and built to specification. The technology using a full LCP build-up and brass metal backing was finally chosen for building the demonstrator due to better manufacturability and electrical performance.
The laser ablation of the chip cavity and adhesion to the corresponding bond pads and the possibility of the ENEPIG plating were demonstrated on the LCP substrate. Wire bonding tests were successful on the LCP substrate.
It would be very interesting to further investigate optimisation of the substrate and its manufacturing costs in a follow-up IMAGINE project. The goals would be to replace chip cavity fabrication by UV laser ablation with CO2 ablation (to decrease process throughput time), to eliminate or replace the back metal brass heat sink with a partly defined back metal heat sink, and, to combine the cost adding high precision and high frequency LCP part with a low cost and low tolerance DC part substrate.
Polymer antenna substrate and metallisation
The objectives were to develop a process for making antenna horns with adequate precision and performance using metallised polymer substrates and to develop the assembly process of the antenna onto the substrate. A thorough analysis of the exact process was carried out once the final design of the horn antenna was complete. The discussion of the manufacturing of the polymer corrugated horn antenna comprised the forming and metallisation processes required for achieving the right functionality of the horn and the choice of methods for large volume manufacturing, as well as rapid prototyping for demonstrating the feasibility of the approach.
It was not possible to perform injection moulding of a polymer based antenna as the costs for manufacturing injection mould tooling were outside the project budget. However, strong collaboration between Acreo and Dyconex resulted in the rapid prototyping of a metalised polymer horn whilst observing the DfM rules established for potential industrialisation. In addition, scoping of the possibilities of manufacturing the horn has been identified together with all relevant partners and third parties.
Standard metallisation processes like galvanic plating and electroless plating were considered as well as physical vapour deposition processes. Machining was used for rapid prototyping the antenna horn and a selection of metallisation methods were tested from the technologies available at Acreo as a proof of concept.
Pieces for the polymer antenna horn demonstrator were manufactured but there were difficulties incurred due to problems making the wrought chosen polymer material. These difficulties caused in turn breakage and defects to many pieces during rapid prototyping as well as metallisation problems. Extra effort was required to solve these problems. Such problems should not exist when injection moulding the chosen polymer in a proper industrialised process. Polymer antenna prototype pieces were finally successfully formed, metallised and assembled that could be subjected to testing in work package 3.
System integration, assembly and testing
The main objective of the project's work package 5 was to test and characterise the fully assembled radiometer module. Two different types of radiometer demonstrator modules were assembled and tested: one using split metal waveguide blocks with the LNA and hybrid detector and zero-biased diode developed in work package 2; one using the LCP PCB demonstrator developed in work package 4 using a commercial chipset.
Integration / assembly of radiometer module
RHe assembled the first prototypes of the 94
GHz single channel radiometer using the low cost high performance LCP substrate manufactured in work package 4. In addition, radiometer modules using the zero-biased diode and LNA designed and manufactured in work package 2 were assembled. In total, five fully functional modules were assembled:
- five test radiometer modules for reference characterisation of LNA chipset;
- two LCP based modules.
For the characterisation of the zero-biased diode, two modules with a single diode flip-chip assembled on to a hybrid and two hybrids with GSG probe-pads were assembled.
Two types of test radiometer modules were produced at RHe, one with a single LNA and one with two cascaded LNAs for additional gain. In respect to the frequency range, very narrow tolerances were specified. A manufacturing flow was created for each of the radiometer modules, the LCP substrate prototypes and the hybrid detector substrates and modules. The challenging part of the assembly was to fit very narrow tolerances for placement and very short wirebonding in order to meet the reference conditions for the chipset mm-wave characterisation. The production flow of the LCP substrate prototype shows clearly the expected improvement of the production flow in order to achieve high performance modules at much reduced cost driving processes.
Testing of radiometer chipset components in-package
Before the final radiometer module was tested, it was important to understand the performance of the individual components, i.e. the LNA and detector, which provide the detecting capability. These components were tested in separate waveguide jigs to understand their isolated performance.
The custom radiometer chipset comprises an LNA and a detector. The LNA circuit, the discrete zero biased diode and their respective RF characteristics are described earlier. A custom hybrid detector, based on the discrete diode, was designed (so that the extra wafer runs required for the zero-biased diode optimisation would not impact work package 5). The hybrid detector consists of the discrete diode flip-chip assembled onto a thin film (alumina) substrate that includes impedance matching structures to achieve the required bandwidth for the detector. This hybrid detector was successfully assembled and is the detector used for radiometer characterisation.
The individual LNA and hybrid detector were packaged in separate split block metal packages. Two variants of the LNA block were packaged, one variant that included a single LNA MMIC and the other that included two LNA MMICs connected in series. The individual blocks for the LNA variants and for the detector have been characterised.
In-package LNA
The LNA has been characterised on-wafer using RF probes to verify the design in work package 2. However, to understand the performance achievable in the application, it is important to characterise the LNA in a package environment where the effects of source and load impedance mismatch and cavity feedback can be seen.
The packaged LNA consists of a split block construction, gold plated aluminium, with WR-10 waveguide interface at the input and output connected to the LNA by input and output quartz thin film RF probes.
The LNAs were tested using two test benches, a noise figure test bench and a vector network analyser test bench.
The NF result is encouraging and demonstrates the low noise capability of the OMMIC D007IH process and the low noise design of the LNA. This result is state of the art for GaAs based substrates and comparable to the NF that can be achieved on more exotic and expensive InP processes. The NF of the LNA and the packaging is one of the key figures of merit for a radiometer and a determinant of the overall system noise and therefore detection capability.
The gain of the LNA with frequency is broadband, covering 70 - 100 GHz. For a passive radiometer, a general design rule is to have as wide a bandwidth as possible to improve the signal to noise ratio and therefore detection. Also, a certain amount of gain is required prior to the detection to raise the signal level above the noise floor of the detector. Two of the single LNAs cascaded together would provide sufficient gain to achieve this. Some problems were experienced with the stability of the LNA when biased for high gain and assembled in the waveguide modules. A selection of damping lid alternatives was fabricated to improve stability and measurement results.
In-package hybrid detector
The hybrid detector was packaged in a split block metal package, similar to the LNAs. The input to the detector is an RF signal and the output is a DC signal.
The test set-up consists of a mm-wave signal source to provide power over the frequency range 75 - 110 GHz and a voltmeter to measure the output voltage. A synthesiser is multiplied to the required frequency, then the signal is passed through a variable waveguide attenuator to set the input power at the detector input. The power level at the detector input is calibrated using a spectrum analyser.
The LCP substrate-based radiometer modules were assembled using the chipset from HRL. During characterisation of this receiver, there were problems encountered thought to be due to stability issues of the package interacting with the chipset. One of the receivers that was produced was damaged due to this problem. The RF components used in the front end have relatively small breakdown voltages. If an oscillation builds up the signal level can damage the actual semiconductor devices.
The second LCP substrate-based radiometer did function and was able to detect small changes in the input temperature. The thermal sensitivity is referenced to the output of the detector and was measured to be about 2.2 µV/K which is in the expected range for the module and would normally yield a receiver with NETD < 1.0K in accordance with the target specification for the passive mm-wave radiometer. However, the output DC voltage level was higher than expected.
To summarise, bench testing of the manufactured and assembled integrated radiometer modules, based on the Dyconex LCP substrate, was completed showed promising results, even though there were a few issues seen during the testing. Testing of the separately packaged 94 GHz radiometer chipset from work package 2 (W-band LNA and hybrid detector circuit with the zero-biased diode) for passive imaging has been completed also. The LNA achieves state of the art noise figure performance, is broadband and achieves sufficient gain for two LNAs to be cascaded together for the required level of pre-amplification prior to the hybrid detector. The hybrid detector achieves broadband matching. However, its responsivity in-package is lower than expected. More investigation is required after the project to understand why. Testing of a complete radiometer incorporating the 94 GHz radiometer chipset from work package 2 has been performed but is not yet completed due to slippage in the schedule.
Performance validation
As described previously, two radiometer modules have been developed in this project. One demonstrates the use of an LCP substrate, the other demonstrates the zero-biased diode and LNA. The performance validation evaluates the radiometer module performance in the system and compares it with the bench characterisation results for noise figure and NETD, in addition to comparing the imaging results with those obtained with the incumbent radiometer.
The demonstrator imaging system, property of GATE S.A. is used to test receivers before integrating them in their imaging product.
The imager has an opto-mechanical scanning system that does not use any frequency selective components and can therefore operate with different frequency receivers, as well as having a theoretical 100 % transmission. It has been designed to work as a passive system. This system has been designed to have a 6 mrad spatial resolution.
The system uses a combination of rotating mirrors to produce a high speed linear scan pattern of ±10 º in the vertical plane. This configuration is combined with a plane flapping mirror that flaps to scan 60 º horizontally in the scene. In this way only one receiver is needed.
A mounting fixture was prepared to assemble the radiometer modules into the GATE demonstrator imaging system. The power supply and acquisition electronics were also adapted and modified for the LCP substrate and waveguide-based radiometer modules. The mounting fixture was designed to also accommodate the reference GATE single pixel receiver. The three radiometer module types are to be tested with the standard pyramidal horn antenna, as seen in the above figures, for comparison purposes.
To ensure that the system operates correctly within the limits set in the technical requirements from work package 1, the IMAGINE radiometers were to be installed in the imaging system and passive images of real subjects hiding objects under their clothing were to be taken. The detection rate was to be compared with the incumbent radiometer solution.
The demonstrator system user interface has been programmed to show the raw mm-wave image next to the automatic threat detection image for the two IMAGINE receivers plus the reference GATE single pixel receiver. The subjective image quality will be compared between the three radiometers, in addition to the detection rates provided by the automatic threat detection algorithm.
Unfortunately, during the in-system performance tests of the LCP radiometer module, the module started to behave incorrectly. After investigation, it was discovered that the LNA in the module was damaged and no signal output was produced by the module.
It will be investigated why this has happened, as the demonstration and validation of this module is of great importance to the project partners and their everyday business, however this will now have to be done outside of the IMAGINE project as there was no time to do this before the project final review. Once able to make the tests, the in-system NETD and NF will be compared to those obtained with the reference GATE single pixel receiver.
The in-system performance and scanner tests were not able to be done on the IMAGINE radiometer module, as lower than expected responsivity was measured for this during characterisation, and further work needs to be done before this validation can take place.
Potential impact:
There have been many results produced in IMAGINE. Some results are exploitable in the short term and therefore can have an impact sooner, for example the development of specific semiconductor products. Some results provide a building block for future work and therefore can be exploited over a longer timeframe, as the technology is demonstrated more. The key results, their use and impact are discussed below.
The key development work carried out in IMAGINE has been centred on the development of the IC front end for passive imaging. As a result of this, IMAGINE has established an EU source (OMMIC) for state-of-the-art semiconductor processing and manufacture capable of supplying chipsets for passive mm-wave imaging applications. OMMIC, building on its background IP in semiconductor capability, has developed novel high sensitivity diode epi-layer growth and processing techniques that are compatible with its commercially released mHEMT GaAs process. This capability will allow the combination of optimum detection and amplification functionality on the same semiconductor substrate, a key enabler toward a low cost passive mm-wave solution.
Prior to IMAGINE, companies interested in generating business from passive mm-wave applications had to rely on wholly sourced US semiconductor parts, that were expensive and at risk of US export regulations. Both of these factors put financial pressure, uncertainty and risk on the operations of EU companies to supply the necessary components for mm-wave markets. Now that IMAGINE has established an EU source for mm-wave semiconductor processing, these risks and issues can be countered and allow EU companies to develop parts for passive imaging markets that are price competitive and secure of supply.
Although a product has not been manufactured that incorporates a detector and LNA on the same semiconductor substrate, the process is in place to do this and the capability will be demonstrated once the diode has a suitable junction resistance (< 10 k?). The impact of having an EU semiconductor source with this capability is that the building blocks are in place for the technology to be exploited not only by consortium members but by other companies. This widens the reach of the advantages gained from IMAGINE. For example, OMMIC will incorporate the developed diode into its standard design libraries and offer these to 3rd party MMIC design companies to design products using its newly developed process. The impact of this will be felt over the medium to longer term (3 - 5 yrs). The third party EU companies will gain as now they have access to state-of-the-art processing that was not previously available. OMMIC will gain from increased revenue, throughput and production learning. The companies in IMAGINE will benefit from preferential pricing and access, and also as now there is a wider design pool, potentially developing more advanced products and with more throughput, the processing costs should be reduced, resulting in a lower cost product.
Opening up the access to these semiconductor processes will result in products for other applications being developed, as designers exploit the technology developed within IMAGINE. As an example of this, we could consider the design of frequency mixers and modulators for next generation communications systems and radar applications.
As well as the baseline semiconductor processing development, several prototype products have also been designed, optimised and manufactured. These include a discrete diode, a hybrid detector (using the discrete diode) and a discrete LNA MMIC. The impact of this is already being seen in the short term as OMMIC have the LNA as a standard catalogue part for general sale.
The development of the hybrid detector was a key step in the product development of the final MMIC detector circuit, which has been designed but unfortunately will not be manufactured in time for completion of the project. However, in the short term the impact of the hybrid detector will be to provide the consortium with an interim detector part for further prototyping. RHe manufacture and assemble the detector, so there will be a positive financial impact to them and OMMIC provide the discrete diode. GATE can use the LNA and hybrid detector to build several sample systems.
IMAGINE also focused on package and antenna development. A key result from WP4 was the development of LCP processing techniques to manufacture an integrated radiometer design where the antenna feed transition (WP3), RF and DC electronics are located on the same substrate. In addition to this, an antenna was developed, based on design rules for injection moulding, which was manufactured from LCP and then metalised. The metalised LCP antenna achieved encouraging results when compared to its metal machined counterpart.
Both of these results provide a sound technology platform for improving the integration of passive imaging receiver front ends and therefore will impact the cost of passive imaging systems. Also, in the future, this technology platform will allow the development of different receiver architectures and therefore also possibly different types of passive imaging systems. For example, smaller form factor, starring array and hand held type devices.
The integration of more functionality at the component level is seen as key to reducing sub-system and general system assembly and test costs, which can be a significant part (50 %) of the overall system cost. Therefore, integrating more at the module level and having an antenna technology that is compatible with the module would lead to lower system costs, improving operating margins and potentially sales growth in a positive way. This in turn would benefit the supply chain within the consortium as the supplier at each different level would benefit from increased revenue.
As well as a direct positive financial impact to the consortium members involved in the supply chain, Dyconex and RHe have also benefited from improving their knowhow of mm-wave processing, manufacturing and assembly techniques and increasing their IP related to these areas. Therefore, they are in a stronger position, as a result of IMAGINE, to offer similar manufacturing services to other potential customers. The impact of this will be seen by other companies who can now access these improved mm-wave manufacturing services and develop more competitive products for their markets.
A limiting factor of current systems is the size and necessary orientation of receivers to fit within the specified optics and scanning mechanisms. With increased levels of integration at the receiver level and lower cost, theoretically more receivers could be packaged together to improve overall system performance without increasing the overall system cost. These new system architectures could result in a migration from scanning system architectures to using different focusing lenses and more 'starring' arrays. This would impact the safety of EU citizens as there would be different types of security systems available for their protection.
The consortium for IMAGINE was established to include the whole supply chain required to produce a mm-wave imaging receiver. The supply chain includes; semiconductor processing (OMMIC), design (TECS, CUT, ACREO), substrate supplier (Rogers), substrate manufacture (Dyconex) and assembly and test (RHe). An impact of the program is that the consortium now has experience of working together and understands the difficulties and challenges of producing a mm-wave receiver. Therefore, an outcome of IMAGINE is that the consortium / supply chain is better placed to make a success of the technology developed.
In summary, the developments at both the semiconductor level and the package level could provide a paradigm shift in terms of the approach to mm-wave imaging receiver design and manufacture. Further work, mainly optimisation for production, is necessary for this to happen (a demonstration action proposal will be submitted for this, as this is in-line with the relevant project partners' current and future business objectives). This in turn could lead to different system architectures that not only service current applications (portal imaging) but also open up new application areas (concealed stand-off, hand held detection) that are more competitive in terms of cost, yet also maintain the required performance metrics.
Socioeconomic impact
Passive imaging technology effectively allows detection of concealed objects beneath clothing. Therefore, one of the main applications of the technology is for security and safety and this is where the biggest social impact will be felt. There are three main security application areas:
1) transport hubs - airports and rail and bus stations;
2) critical infrastructure buildings - court houses, financial centres, museums and other public buildings; and
3) large public events, for example sport and music events.
With the adoption and deployment of passive imaging technology at the centres mentioned above, the levels of security will be improved. This will have an impact to society in creating a greater sense of safety and well-being, resulting in more people travelling and attending events thus also having a positive outcome on the wider economy.
Modern day security measures often rely on police or other government agency presence. With the adoption of passive imaging systems, the amount of person presence at the locations / events described above could be reduced. This would have a knock on impact of reducing the required government security budgets to support transport operations or public events, which would be of benefit to the tax payer. In another scenario, the resources could be redeployed in other public service areas to the greater good of society.
Another application area of passive imaging is in theft prevention. As the technology can effectively 'see' beneath clothing, it can be used as a deterrent for theft prevention. In retail outlets and distribution centres, shoppers and workers alike would be deterred from stealing high value small form factor goods. This would reduce the amount of contraband available on the underground market and reduce the associated costs that companies assign to theft. Therefore companies operating margins would increase, benefitting shareholders and the wider society in general.
In terms of direct economic benefits, there is huge potential for wealth to be created. The market for passive imaging is relatively immature and so has huge potential to grow. With the development of passive imaging technology from IMAGINE, there exists the opportunity for job creation to support the supply chain delivering the necessary products into this market. These jobs all require relatively high skilled labour, so there will be a general increase in the levels of capability, knowledge and IP across the labour force working in this area. Up-skilling the labour force in this way will have a positive impact in terms of worker opportunities, salaries earned and therefore levels of taxes paid that can be reinvested by the government to the greater good of society.
Wider societal implications
In terms of wider societal implications we refer to indirect impacts of the technology to society.
As the market grows for passive imaging, other application areas will emerge to use the technology. These opportunities will either be directly able to redeploy the technology or build on the technological base provided by IMAGINE. In either case, these opportunities will foster further investment, technology development, up-skill in labour, job creation and wealth creation for the wider society.
There could be certain applications of the technology in military environments. These include using the technology as a landing aid in hazardous environmental conditions and using it for people screening at military checkpoints. In these applications, the technology saves the costs associated with damaging expensive equipment, but more importantly saves lives.
Main dissemination activities and exploitation of results
One of the main dissemination activities that has taken place is the publication and maintenance of the project website. It allows the project background, beneficiaries and any non-confidential project results to be freely disseminated to the public. The home page currently presents a general introduction to the IMAGINE project. Contact details and EC funding details are clearly identified on each webpage. The members' area contains folders where confidential project documents are stored and shared between the consortium such as deliverables, meeting minutes, presentations and the consortium agreement.
Several project presentations have been given at seminars and meetings across Europe and a project poster in A0 format has also been created and presented. Further conference presentations are scheduled throughout this year and next.
Customer specific marketing and product launches will take place, once the project results have been optimised and reached a more production-ready state. The project partners are committed to this work, which forms part of their individual business plans, and a demonstration activity will also be presented to pursue this.
An exploitation plan has been prepared which establishes the exploitation and supply chain for each foreground IP developed in the project. Private licensing agreements have been put in place to cover collaborations between the partners to fully facilitate exploitation of the foreground technology. These encompass agreements in respect to the protection of intellectual property, and go on to detail the terms and conditions under which licensing of the technology can take place. This licensing to third parties is seen as critical to the rapid roll out of the technology across the European Union and beyond, speeding the proliferation of the technology and penetration of different market sectors and foreign markets.
In the IMAGINE project, licensing rights refer to the granting of licences to partners within the project consortium at fair and reasonable rates. They are granted to partners who have no direct input to a project result but wish to market the result as a desirable component of their own products in a non-competing market. This preferential access is granted at affordable rates that reflect the collaborative nature of this project where all partners have made at least indirect contributions to the entire technology. Following this principle, three royalty levels have been established:
- 'reduced' = 2 % for the SME partners, for the project results they have paid for;
- 'reasonable' = 5 % for any other project partners;
- 'market' = 10 % for anyone outside the project.
Agreements to supply systems or components or material between the SME partners and the large enterprise partners as a result of the work carried out in this project are restricted in nature (i.e. preclude the future supply to/from other users and material suppliers). The supply chains described in the Exploitation Plan are based on a preferential pricing for consortium members policy, and although the first choice is to maintain these supply chains and importance is given to them being exclusively European, they are not binding.
The process of patenting the antenna and front-end integration concept has also been launched.
The project public website address is:
http://www.acreo.se/IMAGINE
The contact details for the project coordinator (SME partner) are:
Gestión Avanzada de Tecnologías Electrónicas, GATE S.A.
Francisco Pérez-Villacastín
fpvillacastin@gatesa.com
Tel: +34-915-159416
The contact details for the technical project manager (RTD partner) are:
Acreo AB
Duncan Platt
duncan.platt@acreo.se
Tel: +46-863-27854
The contact details for the SME project partners are:
Dyconex AG
Daniel Schulze
daniel.schulze@mst.com
Tel.: +41-432-661169
TECS - Technological Consulting Services s.r.l.
Ernesto Limiti
limiti@ing.uniroma2.it
Tel.: +39-067-2597953
The contact details for the RTD project partners are:
Ommic SAS
Peter Frijlink
p.frijlink@ommic.com
Tel.: +33-(0)14-5106731
Chalmers Tekniska Hoegskola AB
Vessen Vassilev
vessen.vassilev@chalmers.se
Tel: +46-317-721894
The contact details for the other project partners are:
RHe Microsystems GmbH
Sebastian Löffler
sebastian.loeffler@rhe.de
Tel.: +49-352-8419924
Rogers BVBA
John Hendricks
john.hendricks@rogerscorporation.com
Tel.: +32-923-53310