The nonlinear characteristic of an RF front-end results in in-band distortion and spectral regrowth of digitally modulated signals with distortion being dependent on the statistical variation of the signal. In this paper, the interaction of the nonlinear response with the signal is explored using a time-averaged autocorrelation analysis applied to several limiter-amplifier models having characteristics ranging from soft-to-hard amplitude limiting. The analysis is verified by comparing measured and predicted adjacent channel power rejection for a code-division multiple-access amplifier.

The impact of RF front-end characteristics on the spectral regrowth of communications signals

A review on the method for the calculation of the describing function of double valued characteristics is presented here with extension to the inverse describing function problem. With this method the calculation of the DF of a characteristic is obtained by considering the function of the characteristic alone without the need of expanding the output waveform into Fourier series. In addition the method Leads to analytical forms from which the inverse problem, of finding special characteristics from their given describing functions, can be solved.

A review on the describing function calculation of double-valued characteristics. The inverse problem†

http://ieeexplore.ieee.org/iel5/8163/24297/01105468.pdf

L. Wadel

Papers

Describing function as power series