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. It became obsolete in the middle 1950s.
• Modified grown junction transistor or alloy junction transistor having two connections at opposite ends of the base^[1]. It achieved its high speed by reducing the input to output capacitance. It became obsolete in the early 1960s with the development of the diffusion transistor.

Modern tetrode transistors

• Dual emitter transistor, used in two input transistor-transistor logic gates.
• Dual collector transistor, used in two output integrated injection logic gates.
• Diffused planar silicon bipolar junction transistor^[2], 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 transistors having two gates.

References

1. ^ Wolf, Oswald; R. T. Kramer; J. Spiech; H. Shleuder (1966). Special Purpose Transistors: A Self-Instructional Programmed Manual. Prentice Hall. pp. pp. 98–102. 
2. ^ U.S. Patent 4,143,421 - Tetrode transistor memory logic cell, March 6, 1979. Filed September 6, 1977.

External links

• Some application aspects of the tetrode transistors PDF (point contact)
• TRANSISTOR MUSEUM Historic Transistor Photo Gallery WESTERN ELECTRIC 3N22 (grown junction)
• The Tetrode Power Transistor PDF (alloy junction)