Non-Inverting Gain Three-Row Scan - Electronic Circuits V & VI: Front-End Conditioning and Op-Amp Feedback Step by Step

A non-inverting feedback stage keeps the input polarity while the feedback divider sets how much output is needed to make the minus input follow the plus input. The plus-one gain term is exact here only for the stated resistor ratios and ideal op-amp model; real circuits add finite open-loop gain and bandwidth, input offset and bias, resistor tolerance, rail headroom, slew rate, loading, noise, temperature drift, and voltage measurement uncertainty.

The non-inverting gain is easier to scan when the input stays fixed and the feedback ratio changes. 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 non-inverting gain includes the one

With equal feedback and ground resistors, the gain is 2. The 2 volt input becomes 4 volts.

V_{\text{out}}=\left(1+\frac{2\ \text{ohm}}{2\ \text{ohm}}\right)2\ \text{V}=4\ \text{V}

A larger feedback resistor raises the gain

The feedback resistor increases to 4 ohms against the same ground resistor. The gain is 3, so the output is 6 volts.

V_{\text{out}}=\left(1+\frac{4\ \text{ohm}}{2\ \text{ohm}}\right)2\ \text{V}=6\ \text{V}

The third row keeps the same input and divider rule

With feedback resistance 6 ohms, the gain is 4. The same input gives 8 volts.

V_{\text{out}}=\left(1+\frac{6\ \text{ohm}}{2\ \text{ohm}}\right)2\ \text{V}=8\ \text{V}