A 28-GHz CMOS Broadband Single-Path Power Amplifier with 17.4-dBm P1dB for 5G Phased-Array

This paper reports a fully integrated broadband and linear power amplifier (PA) for 5G phased-array. Weakly-and strongly-coupled transformers are compared and analyzed in detail. The output strongly-coupled transformer is designed to transfer maximum power. The inter-stage weakly-coupled transformer is optimized to broaden the bandwidth. Besides, linearity is highly improved by operating the PA in deep class AB region. Designed and implemented in 65-nm CMOS process with 1V supply, the two-stage PA delivers a maximum small-signal gain of 19 dB. Maximum 1-dB compressed power (P 1dB ) of 17.4 dBm and saturated output power (P SAT ) of 18 dBm are measured at 28 GHz. The power-added efficiency (P AE ) at P 1dB is 26.5%. The measured P 1dB is above 16 dBm from 23 to 32 GHz, covering potential 5G bands worldwide around 28 GHz.