Cascaded Switching Capacitor based Multi-phase Three-Level Buck Converter for Communication Envelope Tracking

The evolution of 4G and 5G communication systems improved not only the data transfer rates but also the losses associated with the radio frequency power amplifier (RFPA) of the transmitter/receiver system. When supplied with a constant DC power source, the RFPA has very poor efficiency. Envelope tracking (ET) is a supply modulation technique where the supply voltage varies dynamically to track the envelope of the input radio frequency (RF) signal. A cascaded switching capacitor-based multi-phase three-level buck converter is proposed in this digest as a drain supply modulator. EPC 8000 family eGaN MOSFETS are used to enable the multi – MHz high switching frequency of operation of the converter. A fourth-order low pass LC-filter is designed to enable the zero-voltage switching and to track the 20 MHz 4G LTE band-limited envelope signal. The proposed converter has a peak efficiency of 97.3 % and over 95 % for most of the output voltage range. Simulation results and preliminary experimental results are provided to validate the proposed concept.