APPLYING THE QUADRATURE MODELING TECHNIQUE TO WIRELESS POWER-AMPLIFIERS

This article examines an analysis technique referred to commonly as th e quadrature model and its application to the design and simulation of power amplifiers designed for use in digital cellular applications. T he model predicts key performance parameters accurately, including gai n, output power, average supply current, efficiency and distortion cha racteristics of power amplifiers driven by narrowband signals whose en velopes vary with time, such as multitone sinusoids and digitally modu lated RF carriers. The model is based on a series expansion of in-phas e and quadrature-phase (I/Q) envelope voltage transfer functions deriv ed from the amplifier's gain compression (AM-AM) and phase distortion (AM-PM) characteristics. The article shows that the choice of basis fu nctions and series order utilized in the quadrature model to represent the envelope voltage transfer functions has a significant effect on a ccuracy. Conclusions are drawn by comparing simulation results to both measurements as well as to the results obtained by utilizing other si mulation techniques.