Operational Amplifier Fundamentals Unit 5 – The Inverting Summer
Exercise 2 – Averaging
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to operate an inverting summing
amplifier configured for weighting or averaging application. You will verify your results with a
multimeter.
EXERCISE DISCUSSION
- A fundamental inverting summing op amp can be configured for summing, scaling
(weighting), or averaging operations. - The circuit is configured as a unity gain inverting summing amplifier.
- In a unity gain inverting summing amplifier where R2, R1, and RF are equal in value, the
circuit output voltage equals the sum of the input voltages [VO = - (V1 + V2)]. - If the inputs have different gains, the input with the greater gain has more weight.
- If the input resistors are equal and the feedback resistor equals the parallel value of the input
resistors, VO equals the average of the circuit input voltages. - Any number of input voltages can be averaged if the circuit resistor ratios are maintained.