A 20MHz Supply Modulator Designed for Envelope Tracking Power Amplifier at 42GHz

The work presented in this paper is to demonstrate a method that improves the efficiency of a 42GHz monolithic microwave integrated circuit (MMIC) power amplifier using envelope tracking (ET) techniques. A linear amplifier with wide bandwidth is used as the supply modulator for the MMIC power amplifier. And the MMIC power amplifier is tested under fixed DC supply as well as ET modes using a 5.8dB PAPR 20 MHz 16QAM signal. The experimental results showed that the MMIC power amplifier achieves 6% improvement in efficiency. Digital pre-distortion (DPD) is used to linearize the MMIC power amplifier. After DPD adjacent channel leakage ratio (ACLR) can reach -44.5dBc with an improvement above 6dB.