Systematic stability analysis of a Class-B subharmonic mixer

A systematic stability analysis for predicting and correcting nonlinear oscillations of a Class-B subharmonic mixer is presented. First, a large-signal stability analysis is performed to predict the presence of parametric oscillations in the Class-B subharmonic mixer. Secondly, in order to study the origins of the instability, a circuit analysis is performed incorporating the critical large-signal model parameters. An experimental prototype is designed and measured. Parametric oscillations are predicted and measured around 4.2 GHz. Based on the in-depth understanding of the origins of the instability, a practical stabilization solution is proposed to successfully eliminate the oscillations. Simulation and experimental results are in a good agreement.