Non-Inverting Amplifier

Formula

Description

The non-inverting op-amp configuration applies the input signal to the positive input terminal and uses a resistor divider between the output and the inverting input for negative feedback. The gain is always greater than or equal to unity, set by the ratio of feedback to input resistor plus one. This topology provides high input impedance because the signal connects directly to the op-amp non-inverting input. It is widely used for buffering sensor signals, amplifying differential signals, and in active filter stages.

Variables

• Vout — Output voltage (V)
• Vin — Input voltage (V)
• Rf — Feedback resistor (Ω)
• Ri — Input resistor from inverting input to ground (Ω)

Practical Notes

When Rf = 0 and Ri is open (removed), the gain is unity and the circuit becomes a voltage follower (buffer). The output cannot exceed the supply rails (or slightly less for non-rail-to-rail op-amps). Gain-bandwidth product limits the usable gain at high frequencies.