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Amplifier has Vout/Vin characteristics. Ideally it is straight line. In real world this characteristic has different portions, linear part and curved parts at ends.
As far as the applied signal is small comparing to the nonlinearity of Vout/Vin curve we can speak about small signal gain (Vout/Vin). Of cause it varies with characteristic slope varying. This is the case of linear small signal amplifiers like antenna amplifiers where degree of nonlinearities is small.
At large signals we exploit the majority of the characteristics and the total slope and thus the gain can be dependent on signal amplitude. This is the case with RF power amplifiers where nonlinearities are significant.
Dear adcdac
gain is a derivative function.
on common , the OP-AMP as a follower, the operation point is stable, the derivative charge
is the small signal, and the gain is the small signal
gain.
The amp is used to OSC, the operation is unstable,
the OSC charge is large signal, and the gain is the
large signal gain!
I hope that helps!
small signal gain or linear gain , is the gain calculated in assumption that the bias point is constant tand the operating point didnot change with input signal so the gain is constant
manly depend of the gm of the transistor
the large signal gain is the gain of the amplifier when the signal amplitude is large so the bias point change and hence the gm and tha gian
which results nonlinear behavior
linear gain "small signal gain " simulated by AC analysis . mainly constant
Small signal gain is the slope of output/input curve at a specified point on the curve, i.e., it is the drivative at a specified point. Large signal gain is the output divided by the input. It can also to be considered to be (delta output)/(delta input), where delta input is large. If the output/input curve is linear, the two gains are identical.
Dear bkat:
If the output swing is not large,You can simulate the
max output point's small signal gain and min output point's small signal gain,You can find the gain charge is not very large.
On common simulate the large signal gain ,You can
.DC the input signal and find the output signal,the
large signal gain=(Vout2-Vout1)/(Vin2-Vin1).
I hope that helps
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