A Class-G Switched-Capacitor RF Power Amplifier

Abstract

A switched-capacitor power amplifier (SCPA) that realizes an envelope elimination and restoration/polar class-G topology is introduced. A novel voltage-tolerant switch enables the use of two power supply voltages which increases efficiency and output power simultaneously. Envelope digital-to-analog conversion in the polar transmitter is achieved using an SC RF DAC that exhibits high efficiency at typical output power backoff levels. In addition, high linearity is achieved and no digital predistortion is required. Implemented in 65 nm CMOS, the measured peak output power and power-added efficiency (PAE) are 24.3 dBm and 43.5%, respectively, whereas when amplifying 802.11g 64-QAM OFDM signals, the average output power and PAE are 16.8 dBm and 33%, respectively. The measured EVM is 2.9%.