A 31.5dBm outphasing class-D power amplifier in 45nm CMOS with back-off efficiency enhancement by dynamic power control

Abstract

A transformer-combined fully Integrated outphasing class-D PA In 45nm CMOS achieves 31.5dBm peak output power at 2.4GHz with 27% efficiency, and supports over 86dB of output power range. The PA employs Dynamic Power Control (DPC) whereby sections of the PA are turned on-off dynamically according to the OFDM amplitude to reduce power dissipation at backoff. The PA delivers 24.8dBm average power while meeting 64-QAM WLAN requirements. PAE is 16% when using DPC, which represents a 33% efficiency enhancement compared to the DPC-disabled mode. At lower average power of 20.5dBm, DPC enables a 140% enhancement in average efficiency, hence battery life.