This paper presents a technique for modeling nonlinear distortion of multirate time-varying communication circuits. To properly consider the weakly nonlinear distortion effects in circuits with multiple large-signal excitations, we capture the quasiperiodic boundary condition of the system Volterra kernels using a multivariate formulation. We then extend the model order reduction work of [8][9] to reduce this large multivariate representation for compact modeling. The proposed approach is demonstrated on a heterodyne front-end receiver. 1.