Design multi input analog circuits easily. Compute exact output voltages today.
The operational amplifier inverting summing configuration processes multiple input voltages simultaneously through individual input resistors connected to the inverting terminal. The fundamental governing equation for the output voltage ($V_{out}$) is derived from Kirchhoff's Current Law at the virtual ground node:
$$V_{out} = - \left( \frac{R_f}{R_1} V_1 + \frac{R_f}{R_2} V_2 + \frac{R_f}{R_3} V_3 \right)$$
Where $R_f$ is the feedback resistor, $R_1$, $R_2$, and $R_3$ represent input branch resistors, and $V_1$, $V_2$, $V_3$ signify corresponding input signal voltages.
Follow these quick step-by-step instructions to properly evaluate your circuit design parameters:
An inverting summing amplifier is a fundamental building block in analog computing, audio mixing consoles, and signal conditioning systems. By utilizing the virtual ground concept of an ideal operational amplifier, this circuit scales and combines multiple analog inputs into a single inverted output signal. Engineers frequently leverage this topology because individual channel gains can be tuned independently by adjusting respective input resistor ratios relative to the shared feedback resistor.
Why is the output voltage inverted?
The input signals feed directly into the inverting input terminal of the operational amplifier, resulting in a 180-degree phase shift and negative output polarity.
Can I use unequal resistor values?
Yes, unequal resistors allow you to create weighted summing circuits where each input contributes a different amplification factor to the final output mix.
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