An intermodulation distortion estimation method for linear CMOS circuits

Abstract

Summary This article presents a general, time‐domain method for intermodulation distortion estimation that offers a fast, systematic, and compact formulation. It can be applied to any linear CMOS circuit architecture, with any number of stages, ranging from amplifiers and transconductors to filters, that are characterized by weakly nonlinear behavior. Each CMOS stage of the circuit is modeled as a Gm‐stage with an output current expressed as a more involved function of its input and output voltages, taking into account both powers and cross‐product terms necessary to accurately capture the nonlinear behavior. The proposed method is easily implemented in numerical computing environments like MATLAB or Python and results in a very fast distortion estimation. A number of example topologies simulated in Cadence Spectre illustrate the application of the method and demonstrate its accuracy.