A High Efficiency 780 MHz GaN Envelope Tracking Power Amplifier

Abstract

A high efficiency GaN envelope tracking power amplifier (ETPA) operated at 780 MHz, corresponding to LTE band class 14, is presented. The ETPA was tested with both a 6.6 dB PAPR WCDMA signal and a 7.5 dB PAPR 10 MHz 16 QAM LTE signal. Under the WCDMA signal, a drain efficiency of ~70% with 13.5 dB of gain and 28.6 W of output power was measured. The corresponding NRMSE, ACPR1, and ACPR2 were 1.51%, -45 dBc, and -51 dBc, respectively. For the 10 MHz LTE signal, a drain efficiency of 60% with 13.6 dB of gain and 23W of output power was measured. The corresponding EVM, ACPR1, and ACPR2 were 3%, -45 dBc, and -46 dBc, respectively. Using DPD that corrects for memory effects, results that meet the standard's specifications were obtained. To the best of the author's knowledge, the efficiency values presented here set a new record for power amplifier performance under high PAPR signals for both 5 MHz and 10 MHz modulation bandwidth signals.