Development of PSpice Macromodel for Monolithic Single-Supply Power Amplifiers

I. Pandiev (Tech. Univ. Sofia, Bulgaria)

A simple PSpice macromodel has been 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. Further, the macromodel also takes into account ground reference voltage in the amplifier at a single power supply voltage. The model is imple¬mented as a hierarchical structure suitable for the PSpice circuit simulation platform. The sub-circuit is built using standard PSpice components and analog behavioral (ABM) blocks. The accuracy of the model has been verified by comparing the simulation results of the electrical parameters with corresponding measured values by experimental testing of sample circuits. The comparative analysis shows that the relative error for 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.