An Insertion Loss, Phase and Delay Measuring Set for Characterizing Transistors and Two-Port Networks Between 0.25 and 4.2 gc

A new measuring instrument has been developed for making insertion loss, phase, and envelope delay measurements between 0.25 and 397 398 T H E B E L L SYSTEM TECHNICAL J O U R N A L , MARCH 1966 4.2 gc. The development was stimulated by measurement requirements growing out of recent advances in gigacycle transistor technology and semiconductor amplification for high bit rate PCM systems. The new instrument extends to 4.2 gc many of the operational features embodied in lower frequency instruments previously reported.1'2'3 This new test set is intended for characterizing transistors and general two-port networks, either passive or active, in a coaxial mode between 50-ohm terminations. By use of appropriate transducers, measurement may be extended to noncoaxially terminated unknowns. Of particular interest is the measurement of transistors using a special jig designed to provide a smooth electrical transition between the coaxial geometry of the test set ports and the pig tail lead geometry of the transistor. Waveguide networks are measured with the help of well-matched coaxto-waveguide transducers. Since the need for reliable transistor characterization over the UHF band was an especially strong stimulus to the development of the measurement set, Section II deals with the transistor measurement problem and how it was solved. This section discusses the merits of the selected plan of measurement, the design of the required jigs and fixtures, the abstraction of transistor parameters from the measurement data, and examples of the results obtained.