Determining the intermodulation intercept points by SPICE of weakly nonlinear circuits connected in cascade

The intermodulation intercept points of weakly nonlinear circuits are studied. The output second and third order intercept points are obtained with SPICE intermodulation components. Cascade stages of nonlinear circuits are analyzed and the effect of poor matching in cascade stages is show, this affects the accuracy in the prediction of IP3 by conventional engineering formula.