A wide-band jig for the measurement of the current gain of transistors in the frequency range 20????????1000 Mc/s

摘要

The paper describes a jig primarily intended for the rapid measurement of the modulus of near-shortcircuit current gain of transistors in the frequency range 20????????1000 Mc/s (though phase can also be measured if suitable phase-comparison gear is available). The jig needs no internal tuning adjustments and uses 5 ???????? terminating resistors, so that the corrections needed to give true short-circuit current gain are usually negligible with present-day transistors. The plane of measurement is defined to an accuracy of about 1 mm and the measuring resistors are extended to this plane by means of suitable transmission lines. The transistor leads are accommodated in deep drillings, so that measurements can be made close to the transistor header without cropping leads. A novel method of current injection, using a double coaxial system, simulates an input transformer. Measurements made with a short-circuit from input to output terminals showed jig errors less than 0.2 dB over most of the frequency range, rising to about 0.5 dB at 1000 Mc/s. The paper describes constructional details of the jig, gives examples of measurements made with it, and describes a method, using a second jig, by which phase may be measured.