Tetrode transistor

A tetrode transistor is any transistor having four active terminals.

Early tetrode transistors

There were two types of tetrode transistor developed in the early 1950s as an improvement over the point-contact transistor and the later grown-junction transistor and alloy-junction transistor. Both offered much higher speed than earlier transistors.

Point-contact transistor having two emitters.^[1] It became obsolete in the mid-1950s.
Modified grown-junction transistor or alloy-junction transistor having two connections at opposite ends of the base.^[2] It achieved its high speed by reducing the input to output capacitance and base resistance.^[3] It became obsolete in the early 1960s with the development of the diffusion transistor.

Dual-emitter transistor, used in two (or more) input transistor–transistor logic gates.^[4]^[5]
Dual-collector transistor, used in two-output integrated injection logic gates.^[6]
Diffused planar silicon bipolar junction transistor,^[7] used in some integrated circuits. This transistor, apart from the three electrodes (emitter, base, and collector), has a fourth electrode or grid made of conducting material placed near the emitter-base junction from which it is insulated by a silica layer.
Field-effect tetrode

^ US2666150A, Blakely, Robert T., "Crystal tetrode", issued 1954-01-12
^ Wolf, Oswald; R. T. Kramer; J. Spiech; H. Shleuder (1966). Special Purpose Transistors: A Self-Instructional Programmed Manual. Prentice Hall. pp. 98–102.
^ Wallace, R. L.; Schimpf, L. G.; Dickten, E. (November 1952). "A Junction Transistor Tetrode for High-Frequency Use". Proceedings of the IRE. 40 (11): 1395–1400. doi:10.1109/JRPROC.1952.273968. ISSN 2162-6634.
^ US3229119A, Bohn, Richard E. & Sirrine, Richard C., "Transistor logic circuits", issued 1966-01-11
^ Sylvania universal high level logic (PDF). U.S.A. May 1966. p. 4.{{cite book}}: CS1 maint: location missing publisher (link)
^ De Troye, N.C. (October 1974). "Integrated injection logic-present and future". IEEE Journal of Solid-State Circuits. 9 (5): 206–211. doi:10.1109/JSSC.1974.1050504. ISSN 1558-173X.
^ U.S. patent 4,143,421 - Tetrode transistor memory logic cell, March 6, 1979. Filed September 6, 1977.