X-parameter measurement and simulation of an RF amplifier designed to drive a comb-generator

X- parameters, referred to as the parameters of the Poly-Harmonic Distortion (PHD) nonlinear behavioral model as well, have been introduced as the natural extension of S-parameters to nonlinear devices under large-signal drive. This paper describes the approach and procedure of X-parameter characterization and nonlinear simulation of an RF amplifier designed to drive a comb-generator, including measurement experiment, modeling, and model validation. Firstly, a specially configured Nonlinear Vector Network Analyzer (NVNA) is used to the measurements. Secondly, the X-parameters are extracted. Then the parameters are used with the X-parameter framework in ADS to enable accurate nonlinear simulation of device behavior. Independent NVNA measurements validate the model predictions, and show the inadequacy of `Hot S22´ in predicting such performance.