The Measurement of Transistor Unilateral Gain

The unilateral gain defined by S. J. Mason, is a basic measure of the transfer activity of a two-port. It can be measured in a circuit made unilateral with lossless reciprocal elements. A general method of measurement is described, which in principle uses two reactances only; no transformers are required. The method has been realized in a coaxial-line circuit, and measurements have been made on a few transistors in the frequency range 100 to 900 . The results confirm that the unilateral gain is indeed measured in this circuit. It is suggested that unilateral gain measurements are useful both for research into basic device performance and for the specification of power-amplifying ability.