Nonlinear distortion analysis via linear-centric models

An efficient distortion analysis methodology is presented for analog and RF circuits that utilizes linear-centric circuit models to generate individual distortion contributions due to the various circuit nonlinearities. The per-nonlinearity distortion results are obtained via a straightforward post-simulation step that is simpler and more efficient than the Volterra series based approaches and do not require the high order device model derivatives. For this reason the order of analysis can be significantly higher than that for a Volterra series implementation while fully accounting for all nonlinearity effects. The proposed methodology is not restricted to weakly nonlinear circuits, but can also analyze per-nonlinearity distortion for active switching mixers and switch capacitor circuits when they are modeled as periodically time-varying weakly nonlinear systems. While Volterra series have also been attempted for this same class of circuits, the requirement of device models for all of the high order model derivatives makes such analysis somewhat impractical. The proposed methodology provides important design insights regarding the relationships between design parameters and circuit linearity, hence the overall system performance. Circuit examples are used to demonstrate the efficacy of the proposed approach, and interesting insights are observed for RF switching mixers in particular.