Differential Amplifier Calculator Formula
Understand the math behind the differential amplifier calculator. Each variable explained with a worked example.
Formulas Used
Differential Gain
diff_gain = rf_kohm / r1_kohmOutput Voltage
v_output = (rf_kohm / r1_kohm) * (v1 - v2)Differential Input
diff_input = v1 - v2Variables
| Variable | Description | Default |
|---|---|---|
v1 | Non-Inverting Input (V1)(V) | 3 |
v2 | Inverting Input (V2)(V) | 1 |
r1_kohm | R1 (Input Resistors)(kΩ) | 10 |
rf_kohm | Rf (Feedback Resistors)(kΩ) | 50 |
How It Works
Differential Amplifier
Amplifies the difference between two inputs while rejecting common-mode signals.
Formula (matched resistors)
V_out = (Rf / R1) x (V1 - V2)
Requires R1 = R2 and Rf = Rg for proper common-mode rejection.
Worked Example
V1 = 3 V, V2 = 1 V, R1 = 10k, Rf = 50k.
v1 = 3v2 = 1r1_kohm = 10rf_kohm = 50
- 01Gain = 50 / 10 = 5 V/V
- 02Differential input = 3 - 1 = 2 V
- 03V_out = 5 x 2 = 10 V
Ready to run the numbers?
Open Differential Amplifier Calculator