+117 dbm high-efficiency CMOS power amplifiers operating at high voltage for 24 GHz radar sensor

The authors investigated the series-bias technique suitable for designing complementary metal-oxide semiconductor (CMOS) power amplifiers using scaled-down CMOS technology. The series-bias technique effectively increased the operating voltage of two K-band amplifiers and achieved a high output power level. A two-stage series-bias amplifier showed a small signal gain of 9.5 dB, an output power of 17.7 dBm and a power-added efficiency (PAE) of 10.4 at 23 GHz. A three-stage series-bias amplifier showed a small signal gain of 17.3 dB, an output power of 17.5 dBm and a PAE of 8.8 at 23.5 GHz. The measured output power was the highest for K-band power amplifiers using common-source transistors. These amplifiers employing the series-bias technique are shown to have a highly favourable figure-of-merit compared with the results obtained from conventional amplifiers. The results will be useful for fully integrated radar sensors at microwave/millimetre-wave frequencies.