On the Variation of Transistor Small-Signal Parameters with Emitter Current and Collector Voltage†

Abstract

ABSTRACT The variation of transistor small-signal parameters as a function of emitter current and collector voltage has been investigated theoretically and the results have been compared with those of a parallel experimental investigation. The experimentally determined variations of the low frequency hybrid parameters have been found to be in excellent agreement with the calculations, apart from the variation of h12 with emitter current, which showed a quantitative disagreement with the theory. Misawa's theoretical expression for the cut-off frequency, fα, has been compared with the experimental results and has been found to lead to a wrong dependence on the emitter current.