Non-Inverting Gain Adds One - Electronic Circuits V & VI: Front-End Conditioning and Op-Amp Feedback Step by Step

Non-inverting feedback makes the output large enough that a divider copy matches the input, so the closed-loop gain is one plus the resistor ratio. The 3 ohm, 6 ohm, and 2 V ledger is exact for an ideal op-amp inside its rails; real circuits include input offset, finite gain, bandwidth, resistor tolerance, loading, noise, and measurement uncertainty.

A non-inverting amplifier uses a feedback divider, so its gain is one plus a ratio. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

The feedback divider samples the output

The feedback divider uses 3 ohms to ground and 6 ohms to the output.

\frac{R_f}{R_g} = \frac{6\ \text{ohm}}{3\ \text{ohm}} = 2

The non-inverting gain adds one

The gain is one plus the resistor ratio, so 2 volts becomes 6 volts.

V_{\text{out}} = (1+2)\cdot 2\ \text{V} = 6\ \text{V}