Cardiff Behavioural Model Analysis using a Two-Tone Stimulus

This paper presents a new technique for identifying the mixing structure, model coefficients and therefore model order of the Cardiff behavioral model for phase related nonlinearities. The technique employs a two-tone measurements approach and the Fast Fourier Transform (FFT) to be able to observe the mixing structure above the noise floor of the measurement system. Spectral tone visibility explicitly requires model coefficient inclusion for accurate (NMSE <; -40dB) data fitting, which is verified by comparing model fitting of full and truncated model formulations. The identified maximum phase model order from two-tone measurements, for annuli on the Smith Chart, is shown to be accurate for Continuous Wave (CW) measurements.