Shot Noise in p-n Junction Frequency Converters

T h e shot noise o u t p u t of any p-n junction device in any circuit can be calculated by enumerating t h e possible hole and electron motions and summing t h e noise energies delivered to the load. This method of analysis will be illustrated by applying it to the dc-biased p-n junction (Section I X ) . A more complicated example, and the principle topic of this paper, is the general p-n junction frequency converter (Section X I ) . T h e technological significance of two kinds of semiconductor diodes used as frequency converters will be discussed briefly. Section II will explain how this theory of shot noise stimulated the recent development of low-noise microwave amplifiers using the nonlinear capacitance of p-n junctions. Section I I I ment ions the nonlinear resistor, for which shot noise appears to be a vital problem. T h e "particle-method" formulation of p-n junction theory in terms of the statistics of individual carrier motions (Section VI) is an alternative to the diffusion equations ordinarily used in the analysis of p-n junctions. Either approach leads directly to the impedance of the junction * Supported in part by the U. S. Army Signal Corps under contract DA 36-039 sc-5589. Preliminary reports of this work were given at the Microwave Crystal Rectifier Symposium, Fort Monmouth, N. J . , February 1956, and the I.R.E.A . I . E . E . Semiconductor Device Research Conference, Boulder, Colo., J u l y , 1957. 951