A high-efficiency linear polar transmitter for EDGE

This paper discusses a linear polar transmitter for EDGE signals with a total DC-to-RF efficiency of 56%. The transmitter is digitally-controlled, allowing for adjustments of delay, phase and amplitude. The amplifier is a 880-MHz class-E high-efficiency circuit with +20 dBm output power and a PAE of 70%. Two different supply modulators are compared: a 18% efficient linear envelope tracker and a 79% efficient switched-mode envelope tracker. The transmitter meets the EDGE spectral mask for both cases, showing that a high-efficiency amplifier can be linearized with a maintained high overall efficiency.