- #1

JJBladester

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## Homework Statement

The following voltages are applied to the instrumentation amplifier in the figure.

V

_{in1}=5 mV, V

_{in2}=10 mV, and V

_{cm}=225 mV. Determine the final output voltage.

## Homework Equations

[tex]R_{1}=R_{2}=R[/tex]

[tex]A_{cl}=1+\frac{2R}{R_{G}}[/tex]

[tex]V_{out}=\left ( 1+\frac{2R}{R_{G}} \right )\left ( V_{in2}-V_{in1} \right )[/tex]

## The Attempt at a Solution

This is an odd-numbered problem in the back of my book, so I know the answer should be 1.005 V.

I already know my initial answer (see below) is wrong because it comes out to 1 V and does not take into account V

_{cm}. Since I'm given V

_{cm}but not A

_{cm}, CMRR, or anything else, how do I solve this problem?

Incorrect:

[tex]V_{out}=\left ( 1+\frac{2\cdot 100k\Omega }{1.0k\Omega} \right )\left ( 10mV-5mV \right )=1mV[/tex]