Measurement of transistor high-frequency current gain

Abstract

An approach commonly used in instruments to test the high-frequency current gain of transistors consists of driving the base with a calibrated current source and measuring the collector current with a very low resistance meter. The major shortcomings of such instruments are their insufficient accuracy and their limited range of quiescent test conditions. However, a thorough analysis of this method demonstrates the possibility of reducing the measurement error, in the most unfavorable case, to less than 4.5 per cent as well as the possibility of extending the test conditions to 10µv, 10µa. These improvements were obtained as a result of the development of such features as a source impedance of 50K Ω at 100 Mc, a collector load of 1 Ω and a very low capacitance socket.