Novel Metric Describing Total Nonlinearity of Power Amplifier With a Corresponding Figure of Merit for Linearity Evaluation and Optimization

Abstract

In this work, we present a novel metric for the total PA or Tx nonlinear distortion in form of an output signal nonlinear power. The presented metric takes into account all sources of distortion and it evaluates a nonlinear distortion that appears inside and outside of the signal bandwidth. Furthermore, the FOM that acts as a signal to total distortion ratio STDR is developed. Optimizing the PA or Tx system for maximum STDR maximizes the ratio of the linear over nonlinear power of the output signal. That ensures optimal linearity and output power level. These characteristics make this technique convenient for a overall linearity evaluation and for optimization of the different linearity improvement techniques applied to the PA or Tx system.