AM/AM and AM/PM Distortion Generation Mechanisms in Si LDMOS and GaN HEMT Based RF Power Amplifiers

摘要

This paper provides a comprehensive analysis of the AM/AM and AM/PM nonlinear distortion generation mechanisms arising in the most common RF power amplifier (PA) technologies presently used in cellular infrastructures: the Si LDMOS and the GaN HEMT. Considering all the known nonlinear elements of both transistors' equivalent circuits, namely, the drain–source current and the gate–source, the gate–drain and the drain–source capacitances, semi-analytical expressions are derived for the PA's AM/AM and the AM/PM distortions. This model is shown to offer an accurate nonlinear distortion prediction across the whole range of operation classes (Class C, Class B, and Class AB) and signal ranges (from small-signal to power saturation), and a qualitative view of the physical distortion generation mechanisms, which is useful for nonlinear circuit design and performance optimization.