Development of PSpice Macromodel for Monolithic Single-Supply Power Amplifiers

Abstract

A simple PSpice macromodel was developed, and verified for monolithic power amplifiers operated with a single-supply voltage. The proposed macromodel is developed using simplification and build-up techniques for macromodeling of operational amplifiers and simulates the basic static and dynamic characteristics, including input impedance, small-signal frequency responses at various voltage gains, output power versus supply voltage, slew-rate-limiting, voltage limiting, output offset voltage versus supply voltage ripples, and output resistance. Furthermore, the macromodel also takes into account the ground reference voltage in the amplifier at a single power supply voltage. The model was implemented as a hierarchical structure suitable for the PSpice circuit simulation platform. The sub-circuit was built using standard PSpice components and analog behavioral (ABM) blocks. The accuracy of the model was verified by comparing the simulation results of the electrical parameters with the respectively measured values by experimental testing of sample circuits. The comparative analysis showed that the relative error of the modeled large-signal parameters is less than 15%. Moreover, an error of 15% is quite acceptable, considering the technological tolerances of the electrical parameters for this type of analog ICs.