Determination of the Package Parasitic Inductances of Microwave Bipolar Transistors

摘要

A method is presented for the determination of package parasitic series inductances of microwave bipolar transistors. Possible biasing schemes for inductance measurements are first discussed. It is found that for an easy interpretation of the results, the transistor should be kept passive and reciprocal. Then a method is given, based on measuring the small signal scattering parameters of the transistor in three different bias conditions, namely with the two p-n junctions separately in strong forward conduction and the third terminal left open, and with both junctions forward biased for very small currents. From the measurement results the sums of the series inductances can be extracted, and the inductances are then found by solving a set of linear equations. Results for transistors BFR91A and AT42085 are given.