Envelope tracking GaN power supply for 4G cell phone base stations

This paper introduces an envelope tracking (ET) power supply for 4G cell phone base stations using EPC eGaN® FETs. An analytical loss model is developed for design optimization and verified by a single phase synchronous buck converter using the zero-voltage switching (ZVS) technique. The model is then extended to four phases and is used to design a 60 W ET power supply with 20 MHz large signal bandwidth (BW). At 25 MHz per-phase switching frequency, measured static power stage efficiency peaks at 96.5% with 68 W output power delivered from 30 V. Experimental results demonstrate accurate tracking of 20 MHz 7 dB Peak-to-Average Power Ratio (PAPR) LTE envelope with 92.3% total efficiency, delivering 67Waverage power from 30 V.