A digital polar transmitter with DC-DC converter supporting 256-QAM WLAN and 40 MHz LTE-A carrier aggregation

Abstract

A digital polar transmitter is introduced using 9-b thermometer-coded uniform cells to achieve high linearity for wideband signal. A 960 MHz delay tuner is designed for precise amplitude and phase alignment. An on-chip DC-DC is included for direct battery connection and output power control. Boosted bias improves PA efficiency at low power region. This digital polar transmitter outputs peak power 21.9 dBm with 41% drain efficiency, achieves EVM −30.7dB with 802.11ac compliance of 20 MHz 256-QAM signal, also 4.5%/4.8% with LTE-A 40 MHz carrier aggregation compliance of 64-QAM signal.