Three-Level Hybrid Envelope Tracking Supply Modulator with High-Bandwidth Wide-Output-Swing

Abstract

Envelope tracking is a dynamic supply modulation technique, which is mainly used to improve the efficiency of radio frequency power amplifier. For 5G NR mobile devices, this paper presents an envelope tracking supply modulator which is composed of a three-level switching converter and linear amplifier (LA) in parallel. The hysteresis control method is adopted in the supply modulator to improve the bandwidth of the switching converter and the loop response speed. At the same time, a rail-to-rail input-output class AB linear amplifier is designed to achieve a wide output swing and a super source follower is proposed to reduce the output impedance of LA. Designed with the 180 nm CMOS technology, the supply modulator operated at 5G NR 100 MHz envelope signal. The output power of the modulator reaches 1.5 W for a 6 Ω load resistor and the output swing is 4.3 V at 5.0 V supply, and the maximum efficiency reaches 85%.