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# Why the feedback is: voltage-voltage?

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#### mtkee2003

##### Full Member level 2
amazing feedback!

hi
this simple circuit complicate me!

i know that its feedback is series(current) in output and parallel(current) in input.
but why?!
regards.

Re: amazing feedback!

I dont see any complications here, or I misunderstood your problem

Re: amazing feedback!

This is series-parallel feedback, series at the input, parallel at the output.
However, it is not current, but voltage feedback.

It is easy to see why:
First of all, look at the output side and see how the signal is applied to the feedback network. The output voltage is simply taken right from the output, that is "in parallel" (with the load, if the load was shown, you could see that the load voltage is also applied to the feedback network).

Second, look at the input. The opamp actual input is the voltage between its differential inputs. You apply the voltage at the (+) input of the opamp, with respect to GND. But the (-) input is not connected to GND, it is connected at the output of the feedback network. Therefore, the two voltages (between the (+) and (-) inputs of the opamp, and the output voltage of the feedback network) are "in series".

### mtkee2003

Points: 2
amazing feedback!

Thanks My friend
i say this is voltage-voltage too

but somebody else colmplicate me.(a master!)

regards

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