The spectrum of intermodulation generated in a semiconductor diode junction

Abstract

In this paper exact formulas are found for the intermodulation generated in a semiconductor diode junction, and a method is developed to make the calculation of the intermodulation practicable. This method generates the intermodulation output spectrum by operating on the signal input spectrum with convolution. This method lends itself to tabular, graphical, or computer solutions, and the results can be easily interpreted. In the past the detailed calculation of intermodulation product amplitudes was a formidable task. With the techniques of this paper it should be possible to make these calculations routine. It will be feasible to determine RFI compatibility of new frequency allocations ahead of time, analyze existing RFI problems, and design receivers to work in severe interference environments. Equations are derived for the total intermodulation at a specific frequency, and for the spectrum of each order of intermodulation due to either CW or quasi-continuous input spectra. Examples are given of cross modulation, intermodulation, distortion, and third-order products.