Why the amplifier gain is negative?

Answer 1

Your question is vague. If you are referring to an operational amplifier in the usual configuration, the gain of the closed loop is always negative

Answer 2

Not all amplifiers has a negative gain. For example if you feed the output of a negative gain amplifier to the input of a similar amplifier, the output of the second amplifier is positive with respect to the input of the first amplifier. Negative gain means the output signal increases in the opposite direction to that of the input signal. The reason why it is negative is due to the operation of the transistors in the amplifiers and where the signal is applied as input and where it is taken out as output. Gain is normally measured in absolute numbers. In practice an amplifier with a negative gain will amplify your voice coming from a microphone connected to the amplifier will sound exactly the same if the amplifier was a positive gain amplifier given that both amplifiers have the same absolute gains. I hope this is helpful.

Answer 3

One of the benefits of negative feedback is the stabilization of the voltage gain of an amplifier against changes in the components (e.g., with temperature, frequency, etc. ). If you represent the gain without feedback (the open loop gain) by A0 , then the system gain with negative feedback is


where B is the fraction of the output which feeds back as a negative voltage at the input. The extent of this stabilizing influence can be illustrated as follows:

This stabilization increases the effective bandwidth

Answer 4

It means the output power is lower than the input power or you have not got an amplifier but an attenuator.

Answer 5

It means the output is the opposite phase to the input.

You use this to apply negative feedback.

Some applications could use the positive, (in phase), channel, but not often.

Answer 6

Inverse output