op amp voltage follower

Thread Starter

athulascc

Joined Aug 15, 2014
94
IMG20150416WA0047.jpg

in 2nd problem I can mark A0 , Rin and R0 with help of this model of op amp


but what are others?

are there any advance model?
 

WBahn

Joined Mar 31, 2012
30,071
You need to consider what each of those parameters means and then, with that understanding, determine how you would model it in the circuit.
 

MrAl

Joined Jun 17, 2014
11,489
Hello,

Since others here were nice enough to provide me with better images in times when i couldnt read the originals, i thought i would return the favor and clean up this image and rotate it so it is easier to view. Here is the enhanced image.

So what were your answers for the questions then?
 

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kdillinger

Joined Jul 26, 2009
141
yes. I do not know what are Ios and V0s
also how to add Ib ? it is just current (biasing current) so how to model it?
Ios is input offset current and is the difference between the input bias current from each pin. Stated another way, each input pin will have a bias current: IB+ and IB-. These are both measured and the difference between them is the Input Offset Current.

Vos is the input offset voltage and it is the voltage required at the inputs to ensure the output voltage of the op-amp is 0V.

If you want to model Ib, you simply add an ideal current source on each input to circuit ground. To include Vos, you add a voltage source on the IN+ pin to circuit ground.

A really good site that explains how to build a SPICE model from an op-amp datasheet is here:

http://masteringelectronicsdesign.com/build-an-op-amp-spice-model-from-its-datasheet-part-4/

There are 4 parts, I posted the link to part 4. You will see that input bias current, input bias current, and input offset voltage are modeled.
 
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