The architectural study of wireless communication systems typically requires simulations with high-level models for different analog and RF blocks. Among these blocks, frequency-translating devices such as mixers pose problems in RF circuit simulation since their response typically covers a mix of long- and short-time scales. This paper proposes a technique to analyze and model nonlinear frequency-translating RF circuits such as up-and down conversion mixers. The proposed method is based on a generalized Volterra series approach for periodically time-varying systems. It enables a multi-tone distortion analysis starting from a circuit description and derives simplified high-level models based on the most important nonlinear contributions. These models give both insight in the nonlinear behavior and enable an efficient high-level simulation during architectural design of front-ends of RF transceivers.