A 23–28-GHz Doherty Power Amplifier With a PVT Insensitive Power Detection for Adaptive Biasing

This paper presents a compact Doherty power amplifier (PA) featuring a single transformer balun. A novel envelope power detector architecture is introduced for high bandwidth (BW) adaptive biasing that is insensitive to process-voltage-temperature (PVT) variations. The measured PA attains a saturated power (Psat) exceeding 20.2 dBm and a power gain of 19.5 dB across the frequency range of 23-28 GHz. Moreover, it exhibits a peak power added efficiency (PAE) of 38% and a 6 dB power back-off (PBO) PAE of 27% at 25 GHz. The proposed adaptive biasing scheme enables a modulation BW of up to 800 MHz for a 64QAM signal. Under this setting, the average output power (Pavg) is measured at 11.3 dBm with an RMS error vector magnitude (EVM) of -24.5 dB and an average PAE of 15.5%. The PA is fabricated in Global Foundries 45nm-SOI technology with a compact area of 0.27mm2. To the best of the authors’ knowledge, this work is the first to demonstrate robust performance for Doherty PAs across PVT variations.