The effect of collector resistance upon the high current capability of n-p-ν-n transistors

It is shown that the onset of conductivity modulation of the bulk collector resistance causes an abrupt decrease in hFEat high current density and consequently limits the current range in which a transistor exhibits usable gain. Data are presented which demonstrate the accurate measurement of equilibrium collector resistance from a curve-tracer display. Experimental results showing the effect of partial saturation upon transistor switching time are also presented. Recognition of this phenomenon suggests a reappraisal of the importance of other potential causes of high current hFEdecrease.