For data sheet performance, the ADC requires a reference voltage with low noise and good drive strength to charge the sampled reference input. Because the modulator continuously samples the reference voltage whether conversions are ongoing or not (except in standby and power-down modes), the reference loading is constant, therefore incomplete settling of the reference voltage appears as a gain error to the system. The total system gain error can be calibrated. A 22-μF decoupling capacitor at the reference output and 1-μF and 0.1-μF capacitors directly across the reference input pins filters the reference input. The ADC also incorporates an optional reference precharge buffer for the positive input to buffer the reference voltage.