Numerical noise analysis for nonlinear circuits with a periodic large signal excitation including cyclostationary noise sources

A numerical small signal noise analysis method for nonlinear circuits with a periodic large signal excitation, e.g. mixer circuits and switching circuits, is proposed. For small signal input responses, these nonlinear circuits are modeled as their linear periodic time-varying circuits. First, a numerical calculation method for the time-varying transfer function of a linear periodic time-varying circuit is described. Next, a noise analysis method is proposed for these circuits which contain noise sources modeled as cyclostationary random processes. Thermal noise and shot noise in the presence of periodic large signal excitation are modeled as cyclostationary random processes, each of which is modeled as a set of stationary random processes in continuous time. Aliasing components folded back to the baseband from high-frequency bands are calculated, and their powers are accumulated until their contributions become negligible. Simulated noise figures closely matched the measured values.>