Summing Amplifier Calculator

Calculate the output voltage of an inverting summing amplifier with up to three inputs.

V
V
V

Output Voltage

-6.000 V

Gain per Input-1.00 V/V

Output Voltage vs Input Voltage V1

Inverting Summing Amplifier

Formula (equal input resistors)

V_out = -(Rf / Rin) x (V1 + V2 + V3)

When Rf = Rin the output is simply the inverted sum. Different input resistor values allow weighted summation.

Example Calculation

Three inputs at 1 V, 2 V, 3 V with Rin = Rf = 10k.

  1. 01Sum = 1 + 2 + 3 = 6 V
  2. 02Gain = -10 / 10 = -1
  3. 03V_out = -1 x 6 = -6 V

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