An inverting summing amplifier can perform which operation on multiple input signals?

An inverting summing amplifier can perform which operation on multiple input signals?

• A. Weighted sum of inputs, providing a linear combination.
• B. Random noise generation.
• C. Voltage clamping.
• D. Phase inversion of a single input only.

Answer: (A)

An inverting summing amplifier blends several input signals into a single output by creating a weighted linear sum, with the overall value inverted. The circuit ties each input through its own resistor into the op-amp’s inverting input, while the non-inverting input is grounded. The op-amp forces the inverting node to a virtual ground, so the currents from each input add together at that node and are carried through the feedback resistor to the output. The result is Vout = -Rf (V1/R1 + V2/R2 + …), meaning each input is scaled by the ratio Rf/Ri and then summed, with a negative sign. This is why the operation is a weighted sum of inputs, i.e., a linear combination. The circuit is not intended to generate random noise, nor to clamp voltages, and it does not invert just a single input in isolation—the inversion applies to the total summed signal.

An inverting summing amplifier blends several input signals into a single output by creating a weighted linear sum, with the overall value inverted. The circuit ties each input through its own resistor into the op-amp’s inverting input, while the non-inverting input is grounded. The op-amp forces the inverting node to a virtual ground, so the currents from each input add together at that node and are carried through the feedback resistor to the output. The result is Vout = -Rf (V1/R1 + V2/R2 + …), meaning each input is scaled by the ratio Rf/Ri and then summed, with a negative sign.

This is why the operation is a weighted sum of inputs, i.e., a linear combination. The circuit is not intended to generate random noise, nor to clamp voltages, and it does not invert just a single input in isolation—the inversion applies to the total summed signal.