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THE FEUTEX TOOLKIT

Difference Amplifier Resistor Mismatch

Expose unwanted common-mode gain caused by unmatched resistor ratios.

Electronics workspace● Runs in your browser
01 Your input
02 Your result
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FormulaA+= (1+R2/R1)R4/(R3+R4); Acm=A+−R2/R1
Sources and model references

Worked example

Inputs

Inverting input resistor
1000 ohm
Feedback resistor
10000 ohm
Positive input resistor
1000 ohm
Positive ground resistor
11000 ohm
Common-mode input
1 V

Expected results

Positive-input coefficient
10.08333333 V/V
Common-mode gain
0.08333333333 V/V
Common-mode output
0.08333333333 V

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

  1. Enter the labeled inputs in the indicated units.
  2. Calculate and compare every output against the stated model assumptions.

Try this example

{
  "r1": 1000,
  "r2": 10000,
  "r3": 1000,
  "r4": 11000,
  "vc": 1
}

Accuracy and scope

Ideal op amp; mismatch comes only from the four entered resistors. Simplified analytical model; not a design recommendation or safety certification.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.