Application of X-parameters in Modeling and Designing Power Amplifiers: A Brief Overview

In a wireless transmitter system the RF power amplifier (PA) is an essential component. As the wireless industry develops, more and more sophisticated PA designs are employed in transmitters to satisfy the growing stringent requirements on the overall efficiency and power-delivering capability of the transmitter systems. The core of RF PAs are power transistors. Accurate mathematical models of PAs and transistors are essential for system level engineers and PA designers, respectively. This book focuses on investigating the usefulness of X-parameters in behavioral modeling of RF power amplifiers and power transistors. X-parameters are developed as a mathematical super-set of traditional S-parameters. They extend the description of linear S-parameters to the cases of nonlinear systems, which is achieved by including the measurement of scattering waves of the systems at harmonic frequencies. X-parameters capture absolute magnitudes as well as relative phases of all the scattering waves, providing a promising method for mixed frequency-time domain modeling. The work in this book has proved the usefulness of X-parameter modeling method for different types of RF PAs and transistor.