In the inverting amplifier, the node where the input resistor connects to the op-amp's inverting input is held at what type of voltage due to negative feedback?

In the inverting amplifier, the node where the input resistor connects to the op-amp's inverting input is held at what type of voltage due to negative feedback?

• A. Real ground
• B. Virtual ground
• C. Supply rail
• D. Vout

Answer: (B)

In an inverting amplifier, negative feedback forces the voltages at the two inputs to be as equal as possible. Since the non-inverting input is tied to actual ground, the inverting input is held at a voltage very close to 0 V. This is the virtual ground: it behaves like a ground reference in terms of voltage, but it isn’t physically connected to ground, so current can still flow through the input and feedback resistors. In an ideal op-amp, no current enters the input, so all the input current flows through the feedback path to the output, balancing the network and keeping the summing node near ground potential.

In an inverting amplifier, negative feedback forces the voltages at the two inputs to be as equal as possible. Since the non-inverting input is tied to actual ground, the inverting input is held at a voltage very close to 0 V. This is the virtual ground: it behaves like a ground reference in terms of voltage, but it isn’t physically connected to ground, so current can still flow through the input and feedback resistors. In an ideal op-amp, no current enters the input, so all the input current flows through the feedback path to the output, balancing the network and keeping the summing node near ground potential.