Linearity Improvement Techniques for CMOS Switched-Capacitor Power Amplifiers

Abstract

The CMOS switched-capacitor power amplifier (SCPA) architecture was disclosed by S.M. Yoo, et al., in 2011 [1]-[2]. It enabled the design of fully-integrated radio frequency (RF) transmitters with much higher power-added efficiency (PAE) than previous approaches. Herein, new techniques are introduced that also increase SCPA linearity. Specifically, a new switching scheme decreases the amplitude modulation to phase modulation (AM-PM) distortion. When applied to class-G SCPAs [3]-[4], the linearity using the new switching scheme is improved significantly compared to conventional SCPA implementations. More specifically, the AM-PM non-linearity of the class-G SCPA is reduced by about ~ 4X and the error vector magnitude (EVM) is improved by ~ 3 dB.