Experimental study of the effects of current crowding on noise of bipolar transistors at intermediate frequencies

Abstract

In this paper a new transistor noise model taking into account current crowding and surface effects is proposed. The experimental methods characterizing the model elements are given. The model validity for an extended range of collector currents at intermediate frequencies is established. It is demonstrated that for high current values the transistor noise properties for low impedance sources tend to be determined by shot noise rather than by thermal noise as predicted by standard theories. A modulating effect which increases appreciably the equivalent input current noise generator and correlation terms is found. Methods determining the base resistance are discussed. © 1978.