Wideband envelope tracking power amplifier for LTE application

This paper describes an envelope tracking power amplifier for LTE application with large channel bandwidth up to 30 MHz. For the wideband operation, a supply modulator with accurate and fast envelope tracking is essential. The bandwidth of the supply modulator is increased about 2 times without stability degradation by inserting a zero in a feedback path of a linear amplifier. The supply modulator is fabricated using CMOS process and a power amplifier is fabricated using HBT process. An implemented envelope tracking power amplifier delivers efficiencies of 40.0/39.4/38.5% for 10/20/30 MHz LTE signals at output power of 27 dBm.