## Question:

An averaging amplifier is a summer that provides an output equal to the average of the inputs. By using proper input and feedback resistor values, one can get

$-v_{\text {out}}=\frac{1}{4}\left(v_{1}+v_{2}+v_{3}+v_{4}\right)$

Using a feedback resistor of 10 kΩ, design an averaging amplifier with four inputs.

## Step-by-step

$\mathrm{R}_{\mathrm{f}} / \mathrm{R}_{\mathrm{i}}=1 /(4) \longrightarrow \mathrm{R}_{\mathrm{i}}=4 \mathrm{R}_{\mathrm{f}}=40 \mathrm{k} \Omega$

The averaging amplifier is as shown below: