DAC fine-tunes reference output

摘要

Data converters must have a stable reference voltage to accurately measure or generate analog signals. Such references offer many guaranteed levels of precision and stability. Their variety of output-voltage levels is much smaller, which manufacturers specify as standard values, such as 2.048, 2.500, or 4-096V. You sometimes need to dynamically calibrate the reference, fine-tune its output value, or generate a slightly different value. For instance, when you measure a voltage with a resistive divider, you could adjust the reference voltage to compensate for an error in the divider. You can adjust any three-terminal voltage reference using a resistor, a current sink/source, and a buffer amplifier (Figure 1).