Why references matter
Voltage references set the baseline accuracy for ADCs, DACs, and power management ICs. A poorly characterised reference adds DC error that no amount of digital calibration can remove.
Key SPICE parameters
- VREF — nominal output voltage at 27 °C (typically 1.2 V for bandgap).
- TC1, TC2 — first- and second-order temperature coefficients (ppm/°C).
- PSRR — power supply rejection ratio, modelled as a frequency-dependent source.
- NOISE — low-frequency flicker noise and white noise floor (nV/√Hz).
Setting process corners
Our packages ship with three corner files: typical.scs, fast.scs,
and slow.scs. In Spectre, switch between them via ADE → Setup → Model Libraries.
Run Monte Carlo simulations using the included mismatch.scs file to estimate yield.
Interpreting the output
A well-designed bandgap reference should show VREF within ±2 mV across −40 °C to 125 °C. If your simulation shows larger drift, check that the PTAT and CTAT currents are balanced — the ibias_trim parameter in the model lets you adjust the balance point.