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Why the ppen loop gain of an opamp is expressed by this equation?

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firsttimedesigning

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why is the open loop gain of an opamp can be expressed as the following equation:

Aol = Aol(0) / (1+j (f/f3db))

where,
Aol = open loop gain
Aol(0) = open loop gain of the opamp when the frequency is 0
f = frequency
f3db = 3db cutoff frequency
 

Open Loop Gain

Hi
this is just one pole model.
why not?

for f<<f3db
|Aol|=Aol(0)

for f=f3db
|Aol|=Aol(0)/√(2)

for f=∞
|Aol|=0

why not?

it is the simplest model.
yes, you can use more complicated models depend your circuit and precision.
 
Re: Open Loop Gain

you may use small signal model to get the expresion of gain;
and then you make sure the main pole of ur circuit.
then , i think u get that.
 

Re: Open Loop Gain

I suggest you read Ch7 of :

Op Amps for Everyone (pdf file)

Author: Ron Manchini


You can get it here:

**broken link removed**
 

Open Loop Gain

this is a frequency dominant equation.
 

Open Loop Gain

because the gain depends onfrequency
 

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