High Bandwidth and Compact Envelope Tracking Power Supply Utilizing Switched Capacitor Topology

Abstract

The envelope tracking (ET) power supply has emerged to improve the efficiency of the power amplifier (PA) by supplying a variable voltage that tracks the envelope of the input signal to the PA. Represented by 5G, the future wireless communication technologies are characterized by higher envelope bandwidth and lower base station profile, which puts demanding requirements on ET power supply design. This paper investigates the key features of the switched capacitor topology and the pulse edge independent distribution (PEID) method, and then incorporates them into a unitary ET power supply. Comparing with the regular switched capacitor converter, this ET power supply can only involve minor changes in basic topology, which maintains a compact structure and preserves the merits of the original system being easy to drive. Besides, the corresponding control logic and control sequences are optimally redesigned, which can reduce the switching frequency to 1/n (n ϵ N) of the tracking bandwidth and extend the possible too narrow control pulses. To verify the proposed high bandwidth and compact ET power supply, a prototype with 6-26-V output voltage and 21-W peak output power is fabricated. The experiments are carried out by tracking a 1-MHz sine wave and a 5-MHz bandwidth real communication envelope, the results of which validate the proposed configuration and control scheme.