Out-of-band distortion analysis of envelope tracking technique for power amplifiers

Abstract

This paper presents an analysis of out-of-band distortion components generated by waveform clipping in an envelope tracking technique for the transmitter power amplifier of mobile base stations. Numerical investigations show that the out-of-band distortion components are dependent on the bandwidth and clipped level of the envelope signal of the input signal to the transmitter power amplifier. Based on this dependency, the bandwidth and clipped level are appropriately set in order to suppress the out-of-band distortion components. When the envelope bandwidth is restricted to 60% at the output backoff of 4 dB, the out-of-band distortion components are suppressed by more than approximately 30 dB.