Efficient computer simulation of distortion in electronic circuits

A general-purpose electronic-circuit simulation program is employed to efficiently compute second- and third-order distortion due to weak nonlinearities in bipolar junction transistor (BJT) circuits of arbitrary complexity. The method is based on the Volterra-series representation of the electronic circuit and is valid at all frequencies. The transistors are represented by a simple modified Ebers-Moll model, and the adjoint-network concept is employed to efficiently compute the contribution of each nonlinearity in the circuit to the distortion at the output. The method is illustrated with a practical electronic-circuit example.