UC Davis

Energy demand increases rapidly with industrial and economic development. Fossil fuels, oil, coal, and gas as conventional energy sources are non-renewable and will run out eventually. Their excessive consumption produces a large amount of CO2 which directly leads to the greenhouse effect and climate change. Low-carbon renewable technologies need to be found to solve the global energy crisis. Fusion energy stands out among several alternative energy approaches such as wind, solar, biomass, and conventional nuclear fission, with the advantage of being safe, clean, and virtually inexhaustible. It is difficult to study the fusion energy in the plasma state with the problem of instability under extremely high temperatures caused by the reaction between particles. The magnetic field confinement which usually is a Tokamak device is devised for the burning plasma to keep the particles effectively within its center. To understand and improve the confinement and stability, millimeter-wave and microwave diagnostics are required to monitor the inside status of the burning plasma of its turbulent structures and fluctuations.Two commonly used approaches to microwave diagnostics are microwave imaging reflectometer (MIR) which is an active radar-like system comprised of both transmitter and receiver to analyze the electron density properties and electron cyclotron emission imaging (ECEI) which directly receives the emission signals from the plasma and provides 2-D measurement on electron temperature and its fluctuations. Microwave and millimeter-wave wideband receivers play an important role in MIR and ECEI plasma diagnostics. Previously, V-band (55-75 GHz) and W-band (75-110 GHz) receivers in 90 nm-CMOS and 100 nm-GaAs technologies have been successfully designed, and the W-band one has been deployed for ECEI equipment on DIII-D. This dissertation describes the latest progress in receiver development including the F-band (110~140 GHz) receiver chip development using TSMC 65-nm CMOS technology, W-band (75-110 GHz) receiver chip design using HRL T3 40-nm GaN technology, G-band (130~185 GHz) LNA design using Global Foundries 45-nm RFSOI technology, and the V-band (55~75 GHz) MIR receiver array integration. The F-band receiver chip includes an RF-LNA, actively biased broadband mixer, 2~18 GHz IF-Amp, 36~47 GHz tripler, and a 110~140 GHz driver amplifier. The chip size is 1250 × 1150 μm2 and its total power consumption is 250 mW at 1.8 V bias or 400 mW at 2.5 V. The on-wafer measured conversion gain is 7 dB, NF is 14 dB at 110 GHz, and the RF-IP1dB is -21 dBm. In addition to fusion plasma diagnostics, this 65-nm CMOS receiver is applicable for use in applications such as high-speed local networking around the 118 GHz oxygen absorption line and millimeter-wave test instruments in the post-5G era. The W-band receiver chip has the same circuit blocks as the F-band one, but a larger size of 3 × 5 mm2 and better performance of a higher gain and lower noise figure. Its simulated conversion gain is larger than 25 dB, double sideband noise figure is around 5 dB. The RF-IP1dB is -27 dBm. The G-band LNA as the preliminary attempt for the G-band receiver has a simulated small signal gain of 18 dB and a noise figure of 7 dB. The RF IP1dB is -16 ~ -19 dBm. The V-band receiver chip designed by the former student Jo-Han Yu has been integrated into the receiver module with a feed horn, waveguide-to-CPWG transition, LO multiplier chain, IF amplifier chain, and DC power supplies. The measured conversion gain is larger than 30 dB, and the typical single-sideband noise figure is 16 dB. The receiver modules have been assembled into a receiving array in the enclosure which will be installed on DIII-D with the V-band transmitter to serve as the new generation MIR system for plasma diagnostics.