Comparison of time-domain and frequency domain polynomial fitting

Polynomial models for transistor I-V curves are needed for example for Volterra analysis. The polynomial models can be fitted with least-square error techniques from DC data, measured time-series, or measured spectra. This paper shows that with sufficiently broadband spectrum measurement the time-domain and frequency-domain fitting techniques result in the same model. It is also demonstrated that redundancy can be found in the spectrum, meaning that a significant part of the spectral content can be discarded during the fitting, and one still achieves the same fit.