Define input offset voltage, and explain how it affects the output in non-inverting and inverting configurations.

Define input offset voltage, and explain how it affects the output in non-inverting and inverting configurations.

• A. Vio is the supply-induced voltage at the output.
• B. Vio is the differential voltage required between the inputs to produce zero output; in non-inverting, output error ≈ Vio × (1 + Rf/Rin); in inverting, output error ≈ -Vio × (Rf/Rin).
• C. Vio is the voltage across the feedback resistor.
• D. Vio is the input bias current magnitude.

Answer: (B)

Input offset voltage is the small differential voltage that must exist between the two input pins of a real op-amp to drive the output to zero. It comes from mismatches inside the device and is a fixed characteristic at DC. In a non‑inverting amplifier, the input is applied to the plus input and the feedback network sets the gain to 1 + Rf/Rin. The offset between the inputs behaves as an extra input signal, so it is amplified by the same closed‑loop gain. Thus the output offset is approximately Vio × (1 + Rf/Rin). In an inverting amplifier, the input is applied to the minus input and the plus input is at ground. The offset voltage still appears as a differential input that gets amplified by the magnitude of the closed‑loop gain, giving an output offset of about −Vio × (Rf/Rin). The negative sign reflects the inversion in this configuration. Other options mischaracterize Vio: it is not a supply-induced output voltage, not the voltage across the feedback resistor, and not the input bias current.

Input offset voltage is the small differential voltage that must exist between the two input pins of a real op-amp to drive the output to zero. It comes from mismatches inside the device and is a fixed characteristic at DC.

In a non‑inverting amplifier, the input is applied to the plus input and the feedback network sets the gain to 1 + Rf/Rin. The offset between the inputs behaves as an extra input signal, so it is amplified by the same closed‑loop gain. Thus the output offset is approximately Vio × (1 + Rf/Rin).

In an inverting amplifier, the input is applied to the minus input and the plus input is at ground. The offset voltage still appears as a differential input that gets amplified by the magnitude of the closed‑loop gain, giving an output offset of about −Vio × (Rf/Rin). The negative sign reflects the inversion in this configuration.

Other options mischaracterize Vio: it is not a supply-induced output voltage, not the voltage across the feedback resistor, and not the input bias current.