Transistor with four active terminals
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.