Transistor Noise in Circuit Applications

Linear circuit problems involving multiple noise sources can be handled by familiar methods with the aid of certain noise spectrum functions, which are described. Several theorems of general interest dealing with noise spectra and noise correlation are derived. The noise behavior of transistors can be described by giving the spectrum functions for simple but arbitrary configurations of equivalent noise generators. From these, the noise figure can be calculated for any desired external circuit. Illustrative information is given for a number of n-p-n transistors.