Three-port scattering parameters for microwave transistor measurement

A 1- 12-GHz swept-frequency nondestructive three-port s- parameter measurement system for small-signal characterization of microwave transistor chips is described and its merits are discussed. The parameter f/SUB s/ is defined as the frequency at which the transducer power gain becomes unity and is introduced as a useful and directly observable parameter for the s-parameter measurement system. Some measurement results for TI L-187 transistors are given and a physical interpretation of the s-parameter data is discussed.