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Common gate

Common gate amplifier
Common gate amplifier
A common-gate amplifier is one of the possible configurations of FET electronic amplifier. It is normally used to convert low impedance to high impedance, but is very rarely found in practice.

Characteristics

(The parallel lines indicate components in parallel)
Inherent voltage gain:
g_m (R_D \| R_{load})\,
Input resistance:
R_S \left\| {1 \over g_m}\right.
Current gain:
A_{vm} {r_{in} \over R_{load}}
Output resistance:
R_D\,

Transistor amplifiers