Tetrode transistor
Transistor with four active terminals
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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.
Modern tetrode transistors
- 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