Multistage amplifier

The performance obtainable from a single stage amplifier is often insufficient for many applications, hence several stages may be combined forming a multistage amplifier. These stages are connected in cascade, i.e. output of the first stage is connected to form input of second stage, whose output becomes input of third stage, and so on.

Overall gain

The overall gain of a multistage amplifier is the product of the gains of the individual stages (ignoring potential loading effects):

Gain (A) = A1* A2*A3 *A4 *... *An.

Alternately, if the gain of each amplifier stage is expressed in decibels (dB), the total gain is the sum of the gains of the individual stages:

Gain in dB (A) = A1 + A2 + A3 + A4 + ... An

Inter-stage coupling

Depending on the manner in which the different amplifier stages are connected, one of the following amplifiers may result:


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