A High-Performance CMOS Hybrid Envelope Tracking Power Amplifier for Wideband High PAPR Applications

Abstract

A high-performance CMOS hybrid Envelope Tracking circuit is designed to improve the average efficiency and linearity of an RF power amplifier driven by high PAPR signals. A class AB PA at 0.9 GHz and a dynamic power supply for variable envelope signals are designed and simulated with 180nm CMOS technology with 3.3V supply voltage. The dynamic power supply is a hybrid parallel structure that a switching class D amplifier supplies most of the required current and a linear operational Transconductance amplifier covers high bandwidth requirements and also eliminates output ripples of the switching amplifier. The Efficiency of the envelope modulator for 20 MHz LTE signal with 6 dB PAPR at 24 dBm output power is 68%. The average efficiency of proposed ET PA compared with fixed supply class AB PA for 20 MHz LTE signal at 6dB back-off power is increased from 19% to 37%. By prevention of falling the supply voltage below 1V, the EVM of ETPA is decreased from 12% to 7%.