A behavioural model for reducing the complexity of mixer analysis and design

This article considers an approach for the behavioral modeling of the conversion mechanism in a nonlinear device suitable for the analysis of RF/microwave mixers. The core of the model consists of the conversion matrix of the nonlinear cell under investigation, which represents its linearization around the large-signal state. This approach allows for a straightforward implementation in Computer-Aided Design (CAD) using the conversion matrix constructed from either simulation or measurements, of which the latter is considered here. Model order is significantly reduced due to the absence of the local oscillator signal in the frequency analysis plan. The intermodulation products are calculated in relative amplitude and phase and allocated in the spectrum on the basis of the conversion matrix coefficients. We illustrate the technique by implementing this model in commercial CAD software, which allows an in-depth insight into the conversion mechanism and illustrates the application to the design of a subharmonic mixer.