Summing Amplifier
A summing amplifier is an op-amp configuration that adds two voltages together in addition to adding a gain to the output voltage, such that .
More particularly, an inverting summing amplifier is one that also inverts the sign of the sum. The gain of such a configuration can be expressed as . The figure below visually describes the configuration:
Additionally, a noninverting summing amplifier is one that does not invert the sign of the sum. Its gain can be described as
