Measurement and Modeling for RF Amplifier Based on Carrier Waveform Distortion in Time Domain

Abstract

In this paper, high sampling rate oscilloscope is used for measuring the carrier waveform distortion of CW(Continuous Waves) and modulation signal that passed RF PA(Power Amplifier). The comparison indicates the relationship between them. By generating power sweep CW input to PA, relative output waveform in time domain is captured. Then time domain model of PA output is got when input is quadrature modulation signal. On the view of the mathematical expression, the time-domain model is consistent with the existing concepts such as AM-AM, AM-PM and multi-harmonics. In addition, in order to describe the AM-AM effect of PA output signal at fundamental frequency, this paper also proposed a modified fitting function. Frequency spectrum of PA output is measured. Measurement and simulation based on time-domain model in this paper fits well. It verifies the behavior model based on time-domain measurement.