1. A method of analyzing distortion in a circuit, comprising: determining an operating point for the circuit, the circuit having a linear offset and a nonlinear offset at the operating point; determining a first-order solution from the linear offset and an input having a first input frequency and a second input frequency; determining a harmonic component of the nonlinear offset at a difference between the first input frequency and the second input frequency; and determining a second-order solution from the linear offset and the harmonic component of the nonlinear offset at the difference between the first input frequency and the second input frequency, wherein the second-order solution provides an estimate for a second-order intermodulation product for the circuit.