High efficiency and wideband hybrid envelope amplifier for envelope tracking operation of wireless transmitter

This paper presents a high performance Envelope Amplifier (EA) whose architecture includes a linear stage in conjunction with a switching buck converter (switcher stage). This hybrid configuration provides high efficiency and high linearity for the wideband signal. Using a 10MHz 6.6dB peak-to-average power ratio (PAPR) LTE signal, the proposed hybrid EA circuit achieves an efficiency of 83.7% at the average output power of 13.2W driving a 8Ω resistive load, and the gain of the EA circuit can be maintained at around 11 (20.8dB). In order to evaluate the application of the envelope amplifier, the whole ET system is set up for testing. Measurement results show that the ET power amplifier improves PAE by 10% at an average output power of 35.6dBm (6 dB back off point) with respect to fixed supply power amplifier, and the ACPR1 of this ET Transmitter is less than −50 dBc with digital pre-distortion (DPD) technique.