Publication Details
Sehoon Park



Sensors for Internet-of-Things (IoT) and human-oriented applications in daily lives draw huge attention in consumer markets nowadays. Especially, among numerous sensing methodologies and modulation schemes, frequency-modulated continuous-wave (FMCW) radars are adopted in many modern sensors due to their simple architecture and constant envelope waveform exhibiting a low peak-to-average power ratio. FMCW radars at mm-wave/sub-THz frequencies even present unique advantages of a small form factor and complex sensing capability supported by a high range resolution and small displacement detection capability. These features at high frequencies however come at the cost of additional DC power consumption due to degraded transistor performances approaching fmax. For operation in a power-constrained/battery-operated platform and to be scaled into a MIMO array, radar transmitters (TX), a bottleneck of overall radar power consumption, should be thoroughly investigated and innovated. The goal of this PhD thesis is to investigate, implement and verify the realization of low-power and high-efficiency FMCW radar TXs at mm-wave/sub-THz frequencies. Starting from a brief system study on different sensing scenarios and TX requirements, the TXs in this work propose novel architectures and front-end building blocks to obtain the highest DC-RF efficiency. Two chips are fabricated in 28 nm CMOS technology at 60 GHz and 140 GHz to verify their underlying working principle and design methodologies. The first design is a 60 GHz ultra-low-power FMCW radar TX including the distribution of the chirping local oscillator (LO) signal. The chip has been embedded in a full radar system with which different sensing scenarios have been demonstrated. The radar consumes 62 mW, which is a minimum among the state-of-the-art radars in this frequency range thanks to the minimized DC power consumption of the TX/LO chain. The second design is a 140 GHz low-power and high-efficiency frequency multiply-by-9 FMCW radar TX. It achieves a measured effective isotropic radiated power (EIRP) of 9.4 dBm, a DC-EIRP efficiency of 16.6% with less than 77 mW DC power consumption while exhibiting an antenna gain de-embedded output power of 7.1 dBm and DC-RF efficiency of 9.7% which is the highest efficiency among the state-of-the-art D-band frequency multiplier chains multiplying by more than a factor four.