Symbolic simulation of harmonic distortion in analog integrated circuits with weak nonlinearities

A method for the symbolic calculation of harmonic distortion in weakly nonlinear, continuous-time analog integrated circuits is presented. The method is based upon a simplified approach to Volterra series in the frequency domain. It is built into an already existing symbolic simulator for linear characteristics of analog circuit, called ISAAC. Symbolic expressions for the second and third harmonic and for the harmonic distortion are generated as a function of the fundamental frequency and the symbolic circuit parameters. For large circuits, simplified expressions are derived using an approximation method. In this way, the major contributions to the harmonic distortion can be identified, providing insight into the nonlinear behavior of analog circuits.<>