Instrumentation amplifier calculator

Calculate three-op-amp instrumentation gain, output and first-stage headroom.

Schematic

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Results

Ideal differential output210 mV

Differential gain	21 V/V
Input difference	10 mV

Advanced results

Input common mode	1.01 V
First-stage output A	900 mV
First-stage output B	1.11 V
Minimum ideal rail headroom	13.89 V

How instrumentation amplifier works

Two non-inverting input amplifiers share gain resistor R3. Their matched feedback resistors R1/R2 set the first-stage differential gain. A unity-gain difference stage subtracts the first output from the second. R2 follows R1 and the four difference-stage resistors are matched at 10 kΩ.

V_{out}=(V_2-V_1)\left(1+\frac{2R_1}{R_3}\right)

Ideal op-amp equations with ±15 V supplies. The simulated generic op amp has finite bandwidth and output limits. Keep signal levels within its linear range.

Change the form inputs or click a component value on the schematic. Choose Try in CircuitSim to simulate the configured circuit.

Do the math

Selected input values
V1	1 V
V2	1.01 V
R3	1 kΩ
R1	10 kΩ

Differential gain: $A=1+2R_1/R_3$
$1+2\times\frac{10\,\mathrm{k\Omega}}{1\,\mathrm{k\Omega}}$
≈ 21 V/V
Input difference: $\Delta V=V_2-V_1$
$1.01\,\mathrm{V}-1\,\mathrm{V}$
≈ 10 mV
Output: $V_{out}=A\Delta V$
$21\times10\,\mathrm{mV}$
≈ 210 mV

Instrumentation amplifier calculator

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How instrumentation amplifier works

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