A non-inverting op-amp amplifies a signal applied to the + input. The – input senses a fraction of the output via a resistor divider (Rf feedback, Rg to ground), forming negative feedback that sets closed-loop gain: Av = 1 + Rf/Rg. The circuit provides very high input impedance and preserves signal polarity (0° phase shift at low frequencies). With Rf = 0 and Rg → ∞ it becomes a unity-gain buffer. Output swing is limited by the op-amp’s supply rails and bandwidth; stability requires adequate phase margin. Choose rail-to-rail devices or proper supply headroom to avoid clipping at large amplitudes.
