Final Report Summary - UWB-IR (Study on Low-power Multi-Gbps Ultra-Wideband Impulse Radio at License-free UWB and 60GHz bands)
In the first year of the project, the researcher started collaboration between Japan and Bogazici University. He obtained necessary radio frequency circuit design software and tools through Europractice. He made an agreement and signed a non-disclosure agreement between Fujitsu Japan and then obtained advanced CMOS technology files. After that, he designed 60 GHz impulse radio building blocks for this project. At first, he obtained a 5mm to 5mm square 90 nm CMOS chip area. The chip is designed in Turkey. He travelled to Japan to test and verify the performances of the fabricated circuits. The performances of the chip are lower than the expected ones. By analyzing the measurement results, he redesigned the chip and sent to fabrication one more time.
In the second year of the project, he visited Japan one more time to test the chips at a millimeter-wave laboratory. The results were improved. A low-power and a wide band 60GHz CMOS amplifier design was presented at a local conference. The test results agreed with the simulation. A multi-channel receiver operating between 56 GHz and 70 GHz for coverage of different 60 GHz bands worldwide is implemented with a 90 nm Complementary Metal-Oxide Semiconductor (CMOS) process. The receiver containing an LNA, a frequency down-conversion mixer and a variable gain amplifier incorporating a band-pass filter is designed and implemented. This integrated receiver is tested at four channels of center frequencies 58.3 GHz, 60.5 GHz, 62.6 GHz and 64.8 GHz, employing a frequency plan of an 8 GHz-intermediate frequency (IF). The achieved conversion gain by coarse gain control is between 4.8 dB and –54.9 dB. The millimeter-wave receiver circuit is biased with a 1.2V supply voltage.
The proposed “study on ultra-wideband impulse radio at license-free UWB and 60 GHz bands” IRG project contains two parts, one is on 60 GHz-band and the other is on the UWB band. To work at 60 GHz-band is very costly and requires well established advanced measurement facilities, but recently to do research on UWB is relatively cheaper and more feasible. Therefore, the researcher will benefit the available technology in Turkey. He started to study microwave passive structures, microwave designs using discrete components, and radio frequency integrated circuit for UWB.
End of the of the second year and beginning of the third year he started to work on microstrip and UWB circuits. He worked on microstrip antennas. He designed, manufactured and measured a low-cost wideband microstrip antenna in his laboratory at Bogazici University. Electromagnetic properties of the designed antenna were investigated by using a 3D electromagnetic simulation program based on finite element method (FEM). Designed antenna is realized with fire-resistive (FR4) epoxy substrate and bandwidth is verified to be wide as expected via network analyzer. The antennas of commercial 3-5 GHz ultra-wideband (UWB) transmitter-receiver kits were replaced with the fabricated antennas. When the fabricated antennas are used, up to 400Mbit/s data-rate, the data transfer range is increased an average of 1.8 fold than that when the commercial ones are used.
He also designed a single-element high-gain rectangular patch antenna using a widely available low-cost FR4 laminate. The gain of the single-element rectangular patch antennas is limited by the dielectric loss and the limited radiating area. Instead of using a low-loss substrate and antenna arrays, we inserted an air gap between radiating and ground planes. This air gap reduces both the electric field concentration on the lossy epoxy and the effective dielectric constant of the radiating plane. Therefore, a low-loss and high-gain single element rectangular patch antenna is obtained. To test the proposed idea, the antenna is designed for a 1.26 GHz resonant frequency. To compare the performance the proposed antenna with the standard single-element rectangular patch antenna, a standard rectangular patch antenna is designed and fabricated at 1.26 GHz using the same FR4 laminate. It was seen that that by applying the proposed method, the antenna gain of a single-element rectangular patch antenna has been improved from 1.78 dBi to 9.58 dBi.
He joined a research group at Bogazici University. He consulted a PhD student and helped to design RF parts of an UWB transceiver design project. A 0–960-MHz/3.1–5-GHz dual-band ultra low-power impulse-radio ultra-wideband transmitter is presented at IEEE Transactions on Circuits and Systems II, in 2012. He is also advising RF circuits of the biomedical device and system development projects. A low-power optically powered receiver system designed in 180 nm triple well UMC CMOS technology. Optical transmission is used for both power delivery and signal transmission.
During the third and fourth year, the researcher started to collaborate with the institutions in European Countries. Dr. Norbert Herencsar from Brno University Czeck Republic visited our laboratory from 15/02/2013 to 30/05/2013 as a visiting scientist by the support of the European Union Exchange program. To get to know more European researchers, he attended European Conferences.
We successfully equipped the laboratory to do advanced microwave research. The laboratory has now a one LPKF ProtoMat S103 circuit board plotter, one 2 ports, 10MHz-40GHz ZVA40 Rohde Schwarz Vector Network Analyzer, one DSA8300 Tektronix Digital Serial Analyzer with Dual 20 GHz W/TDR Electrical Sampling Module, one RSA5126A Tektronix Real Time Signal Analyzer 1 Hz-26.5 GHz, two 8 MHz - 20 GHz MG3692C Anritsu Signal Generator, one 0.01 GHz - 20 GHz HMC-T2220 Hittite Portable Signal Generator, one MS2026C Anritsu Vector Network Analyzer Master 2-port, 5 kHz to 6 GHz, and three low noise DC power supplies. We obtained the crucial microwave test equipment to proceed RF research and to do collaborations with European partners.
We presented our scientific achievements, especially in European Conferences. Some of our works related to this research are presented in the IEEE 36th International Conference on Telecommunications and Signal Processing (TSP) in Rome in 2013, in the IEEE 15th International Radar Symposium (IRS) in Gdansk in 2014 and in the 20th International Conference on Microwaves, Radar and Wireless Communication (MIKON) in Gransk in 2014.
During this project nonlinear millimeter-wave pulse detection property of CMOS FETs is studied for high-speed impulse radio in the host institute. To investigate the pulse detection property, a low power 60 GHz multi-Gbps pulse receiver is designed and implemented in a 90 nm CMOS process technology. Receiver structures which are suitable for short-range, high-speed and low-power data communications applications are discussed. To realize a low-power multi-Gbps high-speed short-range wireless communication at 60 GHz millimeter-wave band, the nonlinear millimeter-wave pulse detection property of MOSFETs is studied both theoretically and in a simulation environment. To demonstrate the low-power multi-Gbps pulse detection property, a complete millimeter-wave pulse receiver circuit is successfully designed. The receiver contains a 60 GHz on-chip impedance matching circuit, a CMOS pulse detector, a limiting amplifier and a buffer. The limiting amplifier which will be used in multi-Gbps millimeter-wave pulse receiver circuit is fabricated using a 90 nm CMOS process technology. The limiting amplifier can cover signals up to 6 Gbps and consumes 25mA from a 1.2V supply.
Throughout the Marie-Currie reintegration project, 3 peer reviewed journals have been published, 1 peer reviewed journal is accepted for publication, 8 presentations have been done in the international conferences, 2 presentations have been done in the local conferences, 2 presentations have been done in the local workshops and 1 master thesis was published. The researcher stated his career as a postdoctoral researcher, then he promoted as a long-term assistant professor position and he is successfully continuing his academic career. With the help of the Marie-Currie reintegration grant, we conclude that the researcher is successfully reintegrated into the European research community.