Measurement of hybrid-π equivalent circuit parameters of bipolar junction transistors in undergraduate laboratories

In this paper we report on a simple and accurate technique for the measurement of the small-signal y-parameters of a bipolar transistor at a given DC bias using a standard LCR meter which is readily available in undergraduate electronics laboratories. We demonstrate how the hybrid-π equivalent circuit of the transistor can be extracted from the measurement using a spreadsheet. Practical results are presented and the accuracy of the extracted hybrid-π parameters is checked by comparison between PSPICE simulation and actual measurement of the frequency response of a common-emitter amplifier built with the transistor in question