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difference between large signal gain and small signal gain

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chen_Analog

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large signal gain

what is the main difference between large signal gain and small signal gain
 

difference between large and small signal

In the small signal gain calculations, you assume that the input signal is small enough so that it doesn't change the dc operating point of the device ( hence you assume a constant gm, ro..etc ), i.e. the circuit is linearized around the dc operating model ( a linear model is used to calculate the gain )

In large signal, the signal causes changes in the operating point. So, linearizing the circuit around the dc operating point would yield wrong results. In this case, a full non-linear model of the circuit has to be used.
 
small signal gain

So in spice simulation, when doing AC analysis, the small signal model of the device is employed, but when doing Tran analysis, the large signal model is employed, isn't it?


elbadry said:
In the small signal gain calculations, you assume that the input signal is small enough so that it doesn't change the dc operating point of the device ( hence you assume a constant gm, ro..etc ), i.e. the circuit is linearized around the dc operating model ( a linear model is used to calculate the gain )

In large signal, the signal causes changes in the operating point. So, linearizing the circuit around the dc operating point would yield wrong results. In this case, a full non-linear model of the circuit has to be used.
Click to expand...
 

definition large signal gain

when talking about "small signal gain", "small signal operation", "small signal xxxx", basically it's about linear operation around the quiesient point.

i think in some books, when they use the term "large signal", they're actually talking about "total signal". so just take both dc and ac into account.

and in some other books, when speaking of large signals, you might need to consider nonlinear operation.
 

large signal and small signal difference

chen_Analog said:
So in spice simulation, when doing AC analysis, the small signal model of the device is employed, but when doing Tran analysis, the large signal model is employed, isn't it?
Click to expand...

Yes, you can say that!!!
 

difference b/w small signal and large signal ?

if a small gain of a op is 60db, it dosent mean a 1mv input will cause a 10v output
 

small signal gain pspice

large signal is inslew region
small signal is in linear region
 

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