Author Topic: Two op-amps in parallel  (Read 3282 times)

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Offline limataTopic starter

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Two op-amps in parallel
« on: May 28, 2014, 04:26:49 pm »
Check this sample circuit about two op-amps in parallel.
http://www.intersil.com/content/dam/Intersil/documents/an11/an1111.pdf
 In Figure 2, Resistors Rbm1and Rbm2 were included inside the feedback loop. I don't quite understand how this can limit the offset current?
Thanks.
 

Offline madshaman

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Re: Two op-amps in parallel
« Reply #1 on: May 28, 2014, 05:21:59 pm »
The offset current they're talking about is due to the output of A and B not being *exactly* the same.  Whenever there's a non-zero voltage differential current will flow according to ohm's law, so the resistors are limiting the current which flows between the two opamp outputs, that is Iab = (Va - Vb)/(Rbm1 + Rbm2).

I hope that's what you were asking.
To be responsible, but never to let fear stop the imagination.
 

Offline limataTopic starter

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Re: Two op-amps in parallel
« Reply #2 on: May 28, 2014, 06:15:09 pm »
Thanks. That is what I was asking.
Although in the sample circuit ( figure 2 in the linked pdf), those two resistors should be left out of the feedback loop, otherwise the op-amp output will not see these two resistors.
 


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