New behavioral-level simulation technique for RF/microwave applications. Part II: Approximation of nonlinear transfer functions

摘要

The instantaneous quadrature technique is an efficient tool for nonlinear behavioral-level simulation of RF/microwave circuits or systems over wide frequency and dynamic ranges. In order to obtain accurate simulation results, accurate approximation/representation of the nonlinear transfer functions (or factors) as well as accurate measurement (or circuit-level simulation) of the amplitude (AM–AM) and phase (AM–PM) nonlinearities are required. In this paper, we consider how to approximate these transfer functions (factors) using splines, orthogonal and nonorthogonal series expansions, and evolutionary programming techniques (genetic algorithm and neural networks) with viewpoint of the simulation accuracy. The influence of AM–AM and AM–PM measurement (or simulation) inaccuracy and noise on the entire simulation accuracy is also discussed. Series expansion methods are proposed as a tool to filter out the measurement noise.© 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 238–252, 2000.