if I have a ideal op-amp of an instrumentation amplifier with 2R1, R2, R3, and R4. with v1=Vcm-Vd/2 and v2=Vcm+Vd/2. Finding Ad and Acm: Ad=.5[(R4/(R2+R3) ) (R4/R1 + 1) + (R4 / R1) ] Acm=(R4/ (R2+R3) ) (R4/R1 + 1) ( R4/R1) Would those equations be correct? or Acm=0?
I figured everyone knew what an ideal op-amp instrumentation amplifier looked like. Let me google it for you: http://www.electronics-tutorials.ws/opamp/opamp21.gif With R1=2R1.
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I know what the circuit looks like, but I haven't memorized the resistor reference designators. In fact, I doubt that they are standard.
OK, I got the schematic. In your original post, what does 2R1 mean? You can find the gain equation on the Internet.
Ok, so if 2R1=4k, R2=100k, R3=10k, and R4=10k, Find differential gain and common mode gain, would I use those equations in first post? Assumming V1 and V2 what I put.
No, Acutally I believe Ad=R4/R3(1+R3/R2). I have a problem in my book that states. For instrumentation amplifier a designer proposes R2=R3=R4=100k, 2R1=10k. For ideal components, what is difference mode gain, common mode gain. The solution uses Ad above to get 21V/V and Acm=0. So, not sure what Acm equation is but doesn't look like my equations on original post are correct.
That equation doesn't even contain R1, so it can't be correct. The correct equation is all over the internet.
how is it 2R2? Confused now, as the solution that was provided for the problem I mentioned in previous post, we used the Ad I posted. With Acm=0, so would Acm=0 here?