Questions about Op Amp Circuit

Bryant11 — Thu, 28 Apr 2022 08:06:33 GMT

I still don't understand how Rf and Rs are voltage dividers if its said that no current passes between the 2 terminals. If there's no voltage applied between the 2 terminals, how can there be a voltage drop on either resistor? If there's no voltage drop on any resistor (or at least Rg) what is the point of these resistors being in the op amp circuit in the first place?

Re: Questions about Op Amp Circuit

bobpaddock — Thu, 28 Apr 2022 15:35:42 GMT

Not sure how that question fits with this group, and this feels like a homework assignment, nevertheless:

The best place to start is to find the classic book "IC Op-Amp Cookbook".
Some searching is likely to turn it up.

The Ideal Op-Amp consists of two input terminals of infinite impedance (no current flow), has again of infinity, infinite bandwidth (operates at a speed of infinity) , and an output impedance of zero, while amplifying the difference between its two terminals. While consuming zero energy during operation. Of course a Real World Op-Amp of today has none of those features.

A simple explanation is that the device acts as a servo to make it appear that there is no current flow.

Think of the resistors as 'programming' an analog-computer (Do look up Analog Computers).
Without the resistors the Op Amp has no program so would not know what to do.

Beyond the Op-Amp Cookbook these are a good place to start:

https://www.analog.com/media/en/training-seminars/design-handbooks/Op-Amp-Applications/Section1.pdf

https://www.analog.com/media/en/training-seminars/design-handbooks/Basic-Linear-Design/Chapter1.pdf

Gain and Offset in thirty seconds:

https://www.ti.com/lit/an/sloa097/sloa097.pdf

"Op Amps for everyone":

https://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf

Handbook of Op Amp applications:

https://www.ti.com/lit/an/sboa092b/sboa092b.pdf

Nonlinear Circuits Handbook [Analog Computers]:

https://www.analog.com/en/education/education-library/nonlinear-circuits-handbook.html

Active Filter Cookbook:

https://www.tinaja.com/ebooks/afcb.pdf

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Questions about Op Amp Circuit

Re: Questions about Op Amp Circuit