Non-inverting amplifier · gain check

Explore the circuit

Inspect the configured study, variations and acceptance limits in the Verification workspace. Run the study, inspect its report and compare the result after changing a tolerance or device model.

Calculate the closed-loop gain

The input VIN is 100 mV DC. RF = 90 kΩ feeds the output back to the inverting input, while RG = 10 kΩ connects that input to ground. Negative feedback gives an ideal gain of 1 + RF/RG = 10, so the expected output is approximately 1 V. The amplifier has ±12 V supplies and a 100 kΩ output load.

Run the nominal circuit

1. Open the example. It starts in Verification with a resistor-corner study already configured.
2. Switch to Schematic and use DC operating point for a single nominal result.
3. Measure U1 OUT relative to ground with the multimeter or scope channel selector. The output should be close to 1 V.
4. Return to Verification and run the configured four-corner study. Its acceptance interval is 0.97–1.03 V.

What 1% resistors do to the output

These are calculated resistor corners with the input and supplies held fixed. The smallest gain occurs with RF low and RG high; the largest occurs with RF high and RG low.

Explore the feedback ratio

In a nominal DC capture, change RF to 40 kΩ while retaining RG = 10 kΩ. The gain becomes 5 and the output should become about 0.5 V. Update the Verification variations as well before running a new tolerance study: the original study explicitly uses resistor values around 90 kΩ.

Understand this model's limits

This is a behavioral amplifier. The demonstration has no physical bandwidth or noise model, so it cannot establish a real op-amp's frequency response, noise or stability. Supply clipping and feedback polarity still matter. An output near a supply rail is a reason to check the connections and requested gain.

Components in this demo

Unspecified values come from the component library. Inspect each part in the workbench before using the model in another design.