Complete noise analysis for CMOS switching mixers via stochastic differential equations

A complete analysis of noise in CMOS switching mixers using stochastic differential equations (SDE) is presented. The noise figure is calculated using this analysis which takes both cyclostationary noise sources and capacitive high frequency effects into account. The analysis leads to important design implications for mixer design and shows that some commonly-used approximations for mixer noise calculations can be misleading in certain cases even at low frequencies. It is demonstrated that there is an optimum value for the load capacitor leading to minimum noise figure and maximum conversion gain for the mixer.