Generalized Linear Periodic Time-Varying Analysis for Noise Reduction in an Active Mixer

A simple linear periodic time-varying circuit model is proposed to rigorously analyze the noise behavior in an active mixer. This analysis can be shown to be a generalization of existing LPTV mixer models, which assume that the mixer is a memoryless device and, as a result, is valid for low frequency only. Based on the proposed LPTV circuit model, explicit formulas for noise figure that accounts for the effect of the thermal noise folding and the flicker noise leakage are derived. Our analysis shows that the mixer operating at OFF overlap mode yields a better noise performance. The analysis is validated against simulations and measurements.