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 ϒ
_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.