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COnverters broadband low power high perforMancE for Telecommunications in Space

Final Report Summary - COMETS (COnverters broadband low power high perforMancE for Telecommunications in Space)

Executive Summary:
For the satellite digital communication systems designed in a tough competitive context, the European Space Industry (with the end users represented within the project by EASDS Astrium Stevenage (UK) and Thales Alenia Space Toulouse (FR) requires advanced components in terms of performance, flexibility and power consumption. Indeed, future telecommunications payloads will contain digital processors to make best use of scarce spectrum and to offer best operational flexibility to operators and end-customers.
This puts ever more drastic requirements for Data Converters and in particular onto Analogue to Digital Converters (ADC).
As they are strategic components for satellite communications, the COMETS project research effort on European sourced radiation hardened ADC’s is mandatory:
1. to respond to the demand for such high conversion capacity, currently not available on the market and
2. to ensure long-term European independence.

Starting from system level requirements is fundamental to develop the right ADC expected by the industry and to open wide market perspectives to it.

The project “phase1” lead to the 10bit 1.5GSps rad-hardened and low power ADC (ref EV10AS180AGS), to serve mid-term critical needs of the Space Industry. The ESCC evaluation according to ESCC226900 performed by e2v and the CNES has demonstrated the suitability of EV10AS180A for operation in space environment.

As longer term needs see increasing performances, a 12 bit ADC beyond State-of-the-Art is then focused in the frame of the “phase2” taking advantage of the advanced technology developed by Infineon (B7HF200) and modelling effort on bipolar transistor. This lead to the development of the 12b ADC (e2v P/N EV12AS200AGS). Characterization results exhibits above state of the art performances for high input frequency (>1GHz) at high sampling rate (1.5Gsps)

The total project duration was 41 months.

Specifications derived from advanced system level needs, proven design and radiation hardening expertise, high performance technology and related device modelling have been major assets for the COMETS project and formed the panel of factors that have contributed to the success in the project realizations.

These two ADC are key components for the European space industry to keep control on the design and production chain of the ADC’s for Space telecommunications. This ensures the Europe’s supplying independence for those strategic components.
Project Context and Objectives:
For the satellite digital communication systems designed in a tough competitive context, the European Space Industry requires European sourced advanced components in terms of performance, flexibility and power consumption. Indeed, an increasing proportion of future telecommunications payloads will contain digital processors to make best use of scarce spectrum and to offer best operational flexibility to operators and end-customers. This puts ever more demanding requirements for Data Converters and in particular onto Analogue to Digital Converters (ADC).
As they are strategic components for satellite communications, research on European sourced radiation hardened ADC's is mandatory 1) to respond to the demand for such high conversion capacity, and 2) to ensure long-term European independence.

The COMETS Programme aims at bringing to the Space Industry the European sourced advanced Analogue to Digital Converter.
The goal is to make available an ADC offering outstanding resolution, dynamic performance at low power consumption and radiation hardening to enhance satellite uplink and down link pay-load implementation, in terms of channel count and response to the rapid increase in bandwidth demands.

The consortium’s efforts were driven by e2v (France), a company which offers to the market the fastest ADC's in the world. Consequently, e2v were the designer of the ADCs. Specifications were agreed with key end-users, both main players in the European Space industry (Thalès Alenia Space France & EADS Astrium UK).
The design of ADC’s have benefited from the most advanced SiGe process from Infineon (Germany). Infineon contributed to the COMETS project not only by providing the advanced fabrication technology but also by bringing their skills in RF modelling and process reliability. As modelling of transistors and lines is a key for such beyond state-of-the-art designs, the CNRS cooperated with Infineon and e2v to optimize the simulation of critical elements. CNES (“Centre National d’Etudes Spatiales”) gave their expertise related to space grade and radiation hardened electronic component development, resulting from its historical involvement and support to the space segment of the telecommunication market.

The project was phased in two steps in order to minimize the project risks and to provide tangible results already at end of the first one.

The first step "STEP1" focused on an innovative low power fast ADC with DMUX designed on the existing B7HF200 Infineon technology; this "STEP1" leads to the 10-bit 1.5 GSps rad-hardened ADC updating the level of ‘State of Art’ data converters, to serve the short term critical needs of the Space industry. The evaluation of the devices in performance, reliability and irradiation based on ESCC standard concludes the STEP1.

As medium and long-term needs by the European space industry demand ever-increasing performances, COMETS Project proposed a high dynamic range 12-bit resolution ADC with DMUX with a clock rate of 1.5 GSps. These performances have been the focus of the "STEP2" taking advantage of “STEP1” results, the world-class expertise of the COMETS consortium including the advanced silicon technology developed by Infineon.
The total project duration was 41 months (only 5 months beyond the 36 months original duration).

The project was then shared in seven work packages as described in the work diagram attached.

So WP1 corresponded to the design phase by e2v of the 10b ADC. This phase has benefited of outcome of the 1st development supported by ESA.
WP2 focused on the validation and characterization phase by e2v and end-users of the 10b ADC. This WP was led by the Thales Alenia Space.
In the WP3 (lead by the CNES), the 10b ADC was evaluated in term of, reliability, irradiation assessment and screening based on the ESCC2269000 (European Space Components Coordination standard). This concluded the step1.

The second step focused on medium to long term needs to propose a 12b resolution ADC with an unprecedented clock rate of 1.5Gsps taking advantages of Step 1 results as well the modeling and technology improvement outcome of WP4 ( lead by Infineon). WP5 was the design development phase. This step 2 will has been concluded with the validation and characterization of the 12b ADC by e2v, TAS and EADS ASTRIUM in the WP6. To note 12b ADC ESCC evaluation and space qualification are not part of the project scope.

Step 1 Main outcome: 10b ADC1.5Gsps
The 10b ADC is based on design on B7HF200 (SiGe) technology from Infineon that is a full vertical isolated bipolar transistor and offer low power together with high speed operation and inherently radiation robustness so suit for space application. This ADC is single core architecture (not interleaved) that does not need calibration over frequency region and/ or temperature range operation.
This architecture ensures with very low latency with 4 clock cycles pipe line delay that is quite safe in regards to radiation issue (SEU SEE) that could appears.
The 10B ADC features 8.5 ENOB (Effective Number Of Bit) together with 60dB of SFDR( Spurious Free Dynamic Range) at 1.5Gsps in L band and Fin equal to 1800Mhz and a Noise Power Ratio ( NPR) of 43 dB with 500Mhz pattern. (Ultra wide band pattern) enabling direct undersampling ultrawide band pattern in the L band region simplify and improve performance of the receiver system by removing down conversion stages, saving system global power consumption.
Hence it offers more flexible operation together with system cost reduction.
Full scale input voltage span 0.5Vpp in one hundred ohm ( input power of -5dBm) is very convenient to ends users to drive the ADC especially at high frequency.
The total power consumption including a DMUX1:4 LVDS compatible logic is 1.9 watt maximum.
Temperature range for Tcase = -55degC up to Tjunction = 125degC.
The package is in ceramic and hermetic dedicated to space application. This package is custom has been designed in order to optimize high frequency operation.

A full evaluation according the ESCC226900 standard (in the frame of the WP3) is performed to proof the suitability of operation of the ADC10b 1.5Gsps in a space environment.
10bit ADC has been included on the ESA European Preference Part List.

Step 2 Main outcomes: 12b ADC1.5Gsps
Making a 12 bits ADC is not as simple as just adding 2 additional bits of the existing 10 bits ADC
On the performances it means improving the SNR performance and SFDR by at least 6 dB and one more bit of ENOB in same operating condition (1.5G L band) with a the lowest possible power trade off.
To minimize the risk, the same proven base line (fully differential) used for the 10b ADC has been used; The scale input voltage span is still 0.5Vpp in one hundred ohm ( input power of -5dBm) despite it is even harder to achieve on a 12bits but ( still relaxing constraint at system level) in Lband. One of the key points is also the power consumption and so defines the trade-off between speed and power. ENOB is better than 9dB. This is compliant to final simulation and last agreed specifications but lower than the initial target. This architecture offers the main advantage to not need calibration over frequency region and/ or temperature range operation. To be noted that is is a key advantage with regards to US competition.

Making this gap has been achievable thanks additional modelling notably of the vertical isolated PNP transistor and complement of modelling on the non-linear zone of the NPN transistor to help designers to optimize the design and of course design improvement.

This low power, high performance rad-hardened 12-bit 1.5GSps ADC & DMUX should provide the following benefits to the European space community:
• Allow to remove stages of RF down-conversion thanks to the wide analogue input bandwidth resulting in significant cost, mass and power savings.
• Provide customers with as yet unattainable dynamic range and NPR (Noise Power Ratio) performance for competitive next generation broadband applications.
• Open new opportunities in existing markets such as cellular communications, broadband multimedia.
• Decrease the number of conversion chains and associated costs (both fixed and operating costs) by the capability to process 500 MHz bandwidths of data.
• Allow to revise and optimize the frequency plan thanks to the flexibility of a fully digital payload.
• Ensure future-proof compatibility in digital output interconnectivity as digital processing component speeds and capacities for space applications advance in the future.
• Be ITAR free
Project Results:
The attached file gives all simulation, manufacturing and characterization results.
It can be noted that the EV12AS200 ADC offers a significant increase of performance compared to 10 bit EV10AS180 ADC, especially in term of NPR (around 3 dB), ENOB (around 0.6 bit) in particular, and SFDR (roughly 2 to 5dB).
Evaluation test programme demonstrate the suitability of those ADC product for operation in space environment.
Potential Impact:
1- Impacts for e2v

The project started in 2010 and one of the achievements is the successful design of the 10b ADC @ 1.5Gsps an d 12b ADC @1.5GSps ADC’s (Analog to Digital Converter) featuring state of the art performances especially at very high input frequency.
Those ADC have been successfully developed by e2v in partnership with Astrium and Thalès Alenia Space (TAS).

Considering its unmatched performances, these ADC also gave rise to interest over the whole industry worldwide in the space market but also adjacent industrial market.

All figures show that the ADC’s developed in FP7 COMETS project is a great technical achievement for Europe, as its direct competitors are in the US. More over, the European space industry keeps control on the design and yet to come, production chain for such high-level devices which ensure the supplying independence of Europe

The main advantages brought by the broadband L Band, 12b 1.5GSpsADC to the Satellite market for the digital payload are:
• Allow for optimizing use of scarce spectrum
• Bring flexibility to operators (re-configurability)
• System simplification (possibility to remove down conversion thanks to L Band)
• European sourcing (No ITAR procurement issues) (design / wafer manufacturing / assembly / test)
The mains space applications are:
• Digital payload in Telecom satellite
• SAR radar (e.g. Earth observation)
• Positioning
Other applications in adjacent markets are
• Acquisition board COTS
• Defense applications

Space Market
Thanks to new satellites and replacement orders, satellite manufacturers are creating a balance between available capacity and new demand. This is expected to provide a sustainable market for satellite manufacturers, and subsequently to Space level component manufacturers such as e2v.
The satellite manufacturing market is dominated by six major manufacturers Thales Alenia Space (TAS) and Astrium in Europe, Boeing, Lockheed Martin, Orbital Sciences, and Space Systems/Loral in the United States. These manufacturers serve #35 different satellite services operators within a cyclical market.
Intelsat, SES Global and Eutelsat represent a very significant part of the satellite operators and as such their impact on the market is very important.
Evaluation of Space market for the 12b ADC developed in COMETS

Competition
Regarding Fast Broadband ADC’s e2v is facing key players all located in the US. Main competitor is TI (US).
E2v as such is the only ADC vendor in Europe to be able to produce ADC (and DACs) with high-end performance beyond competition, especially at very high input frequency, allowing significant system simplification.

Product durability
For over 25 years e2v Grenoble has been providing high performance products to the Space market worldwide. e2v’s broad capabilities in terms of hermetic packaging and test are unique in Europe. This capacity is supported by a reliable product obsolescence mitigation strategy dedicated to long term support of customers’ needs.
The duration of availability of the 10b & 12b/1.5GSps ADC’s and developed in the frame of the COMETS project, is beyond 5 years after the device is placed on EPPL.

CONCLUSIONS
E2v foresees a low volume but very high added value market in Space activity which fully the justifies the development of the 12b ADC which has taken place in COMETS FP7 project.
This will have to be followed by the Space qualification and ESCC evaluation of the 12b ADC in the frame of the ITT ESA funding.

2- Impacts for ASTRIUM

Digital payload processing capability is a key technological enabler for operators of telecommunication satellites. The ability to digitally route traffic, dynamically adjust power and coverage in response to changing link budgets is a key requirement actively sought by commercial operators of telecommunication satellites.

ADC convertor technology is the essential front-end of all digital payload processors. The new 10 and 12-bit ADCs from e2v provide Astrium with options when selecting mixed-signal convertors for future digital payload processors.

The e2v ADCs have been architected to allow direct digitization of L-band carriers making future DSPs lighter, smaller, less power consuming and lower cost. Astrium Ltd. evaluated the 10 and 12-bit ADCs developed by the COMETS project.

For the 10-bit part, Astrium measured a full-scale, baseband, single-tone performance between 8 and 8.2 bits when sampling at 1 GSPS.

The baseband NPR measured from the 10-bit ADC ranged from 39.5 to 42.5 dB when sampling at 1 GSPS. This is equivalent to a dynamic broadband performance between 8 and 8.5 bits. The L-band NPR measured from the 10-bit ADC ranged from 26 to 40 dB as a function of sampling frequency.

For the 12-bit ADC, Astrium measured a full-scale, baseband, single-tone performance around 9 bits when sampling at 1 GSPS. The UHF and L-band NPR measured from the 12-bit ADC was 48 dB when sampling at 1 GSPS. This is equivalent to a dynamic broadband performance of 9.3 bits.

A number of key observations were made during the development of the 10 and 12-bit ADCs regarding specification, performance, packaging, using the evaluation hardware and Simulation support. All of these suggestions have been shared constructively with e2v to ensure their ADCs are fit-for-purpose, benefit the space industry, as well as delivering added value to our customers.

Astrium Ltd. is working with its customers to identify missions that can baseline the new e2v range of space-grade mixed-signal convertors. We are now seeing success for a number of different applications including telecommunications, navigation and Earth observation.

3- Impact for INFINEON

The first obvious impact is creating additional market opportunities for its leading-edge SiGe high speed technologies. Such technologies allow the design of very competitive high performance RF applications. On the other hand typical volumes for such applications are rather low. Additional opportunities, like the telecommunication applications in space investigated in this project help to broaden the application, which is key for assuring the availability of such high-speed semiconductor technologies at reasonable fabrication costs in Europe. This also helps to safeguard the related direct and indirect employment.

But the impact of the COMETS project goes far beyond this. It provided an ideal environment for bringing together not only semiconductor technology provider and application designer at a very early stage of product development, but especially also enabled a close cooperation with academia, in this case with the very advanced CNES characterization and modeling laboratories. By demonstrating the advanced capabilities of these research institutions on the specific COMETS example this establishes contacts and networks that extend the impact beyond the COMETS project itself for future research and development projects.

A part of the gained knowledge on new devices and advanced characterization was also published in peer reviewed international journals and conferences, contributing to advancing the scientific state-of-the-art, see the list in section 2. As a further effect the close cooperation between industry and academia also ensured that graduate students in their PhD research work gained experience with real life examples from modern technologies and applications, in this case especially with an advanced European SiGe HBT technology. This is a clear impact on Europe’s graduate education, beneficial for both, industry and the academic institutions.

4- Impact for TAS

TAS customers demand is moving to more and more capacity but with reduced power and mass impact.
For TAS, COMETS project represents a wide step in the way to be able to respond to such an ambitious demand. In fact it has played to major roles.
The first one is of course that it has given access of a very wide band A to D converter for space application. Indeed, with the complete evaluation for space environment of the EV10AS180 ADC, a very wide band quite low power component is available for short term demands, and the EV12AS200 lets have access to even significantly higher performance, with similar technology, thus space compatible.
But, furthermore than that, its activity during the project has allowed TAS to be able to manage such sharp and sensitive components in term of implementation and solution of electrical issues for space applications, which is mandatory to be able to achieve the customers expected performance.

5- Impact for CNES

In the frame of COMETS project, the ESCC evaluation of 10bits EV10AS180 ADC was performed and all results were satisfactory. With this high quality level reached, E2V 10bits ADC can be used in space equipments. The development of 12bits EV12AS200 ADC was achieved in frame of COMETS. Here the results are lower because this product will be not offered by E2V for space applications

6- Impact for CNRS

The benefit of IEMN from its participation is mainly in increase in academic knowledge. This project gave us the opportunity to:
• further improve our S parameter measurement and noise Figure extraction methodology on new bipolar transistors.
• better understand the physical key parameters required to realize high frequency, high resolution ADC
• Finalize the development thermal test bench base on the IR-camera
• publish a paper at Proceedings of 6th European Microwave Integrated Circuits Conference, EuMIC 2011, Manchester, UK, october 10-11, 2011, 386-389, ISBN 978-1-61284-236-3

The benefit for XLIM is in improvement of technical skills concerning
• Electro thermal modelling of SiGe transistors based on low frequency S parameter measurements
• Narrow pulsed I/V (50 ns) characterisation knowledge for ultra fast semiconductor devices.
• Non linear model in both SDD format and Verilog format for implementation in ADS Agilent and Cadence CAD tools
Two papers have been published
• Compact RF Non linear electro thermal model of SiGe HBT for the design of broadband ADCs:
A Saleh,A EL Rafei, T Reveyrand ,R Sommet, JM Nebus, R Quéré
International Journal of microwave and wireless technologies, Vol 4, issue 06, pp. 569-578. , December 2012
• Experimental characterization and modelling of the thermal behavior of SiGe HBTs
A El Rafei, A Saleh, R Sommet , JM Nebus , R Quéré
IEEE Transactions on electron devices vol 59 ,N° 7 ,pp 1921-1927 , July 2012
List of Websites:
www.comets-fp7.eu