A Junction Transistor Tetrode for High-Frequency Use

If a fourth electrode is added to a conventional junction transistor and biased in a suitable way, the base resistance of the transistor is reduced by a very substantial factor. This reduction in ¿b permits the transistor to be used at frequencies ten times or more higher than would otherwise be possible. Tetrodes of this sort have been used in sine-wave oscillators up to a frequency of 130 mc and have produced substantial gain as tuned amplifiers at frequencies of 50 mc and higher.