Single-Input Relay Charging Switched-Capacitor Topology for High-Bandwidth Envelope Tracking Power Supply

Switching converters are the key parts of envelope tracking (ET) power supplies. To achieve a high tracking bandwidth, the ratio of the switching frequency over the envelope bandwidth is often far larger than 1. The pulse edge independent distribution (PEID) method can reduce this ratio to 1/n (n N), significantly promoting the high-bandwidth tracking capability. However, multiple isolated voltage sources are required, leading to increased system complexity. Based on the PEID method, this article proposes a switched-capacitor ET power supply, which employs supplementary switches to flexibly link all the switched capacitors so that more charging loops are created and the relay charging mechanism is formed, which can equivalently extend the charging time and achieve more balanced voltage levels between the switched capacitors. Thus, with only one input, all the switched capacitors can maintain a stable and equal voltage and, thus, competently serve as the isolated voltage sources. To verify the proposed configuration and control method, a prototype with 2-27 V output voltage range, 54 W peak output power, and 10 MHz tracking bandwidth has been built and tested. The experimental results validate the proposed scheme.