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

Abstract

This letter 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 $(\mathbf {P_{\mathrm { sat}}})$ 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 64-QAM signal. Under this setting, the average output power $(\mathbf {P_{avg}})$ 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 45-nm-SOI technology with a compact area of 0.27 mm2. To the best of the authors’ knowledge, this work is the first to demonstrate robust performance for Doherty PAs across PVT variations.