Check the noise configuration
- In Verification, select ngspice and Noise spectrum & integrated RMS.
- Keep the band at 1 Hz–100000 Hz, input-reference source V1, output at the resistor midpoint and negative terminal at ground.
The analysis has a defined frequency band, output pair and independent input reference.
If you get stuck: If ngspice is unavailable, ask your instance administrator to install/configure it. Native simulation does not perform this noise analysis.
Run three temperature points
- Confirm Temperature sweep with −40, 27, 85 °C and Integrated output RMS noise as the measurement.
- Run 3 cases and inspect the table.
Output RMS is about 0.802, 0.910 and 0.994 µV, respectively, over the stated band. All cases pass the demo limits.
Read the chart and result correctly
- Inspect a run: the chart shows density in V/√Hz, while the table shows integrated RMS in V.
- Compare cold and hot cases. Review the selected run's provenance and download Report JSON.
You can identify which value is density and which is the integrated noise voltage.
If you get stuck: Do not take the ordinary RMS of density samples. The integrated value comes from ngspice. Ideal behavioral op-amps do not acquire realistic device noise merely by selecting this mode.
Extend the temperature workflow
- Save/download any work you want to keep, then use Examples to open Diode bias · temperature study.
- Inspect the diode's attached numeric model and run its three operating-point cases.
The synthetic diode model's forward voltage decreases from about 0.770 V at −20 °C to 0.597 V at 85 °C.
If you get stuck: Only temperature-dependent models respond. Attached numeric model cards require ngspice; this example is not a manufacturer-qualified device.