A K-band UWB CMOS pulse-mode radar transmitter

A 20 GHz UWB radar transmitter in TSMC 90 nm CMOS is designed and measured. The transmitter includes a Gilbert cell mixer, LC-tank oscillator and a pseudo-Gaussian pulse generator (PG). The zero order pseudo-Gaussian pulse is mixed with the high frequency signal to shift the UWB pulse up in frequency. To fit the high frequency pulse to the regulations the PG is implemented with tunable bandwidth and pulse slope. The bandwidth can be tuned from 800 MHz to 2.8 GHz (-10dB bandwidth) and the 20-80% rise time of the slope can be tuned from 108 to 138 ps. The measured results show a 2.5 GHz bandwidth pulse centered at 20 GHz with very low side-lobe levels.