A 23-30 GHz 4-Path Series-Parallel-Combined Class-AB Power Amplifier with 23 dBm Psat, 38.5% Peak PAE and 1.3° AM-PM Distortion in 40nm Bulk CMOS

This paper presents a 4-path series-parallel combined highly-efficient class-AB power amplifier (PA) with broad bandwidth and low AM-PM distortion in CMOS process. Frequency staggered tuning scheme enables a wide passband of 23-30GHz. AM-PM distortion is minimized by utilizing PMOS varactors that mitigate the voltage dependence of transistor intrinsic capacitors and harmonic traps that minimize common-mode voltage swings at the second-harmonic frequency. Complete electromagnetic modeling ensures the proposed PA achieve its full potential. Fabricated in a 40nm CMOS process, the PA achieves 38.5% peak power added efficiency (PAE), 23.0dBm saturated output power (P
sat
) and 20.4dBm output 1-dB compression point (P
1dB
) with 29.5% PAE. The peak PAE is above 35% and P
sat
/P
ldB
remains above 21.5dBm/19.5dBm across 23-30GHz respectively. The minimum normalized AM-PM distortion is less than 1.3°at 26 GHz and remains less than 4.4°across 26-30GHz. Measured EVM/ACLR is below -29dB/-29dBc with 64QAM 5G-NR modulated signal at 28GHz.