A digital-to-analog converter with a voltage standard reference

Commercially available 20-bit digital-to-analog converters (DACs) have the potential to impact the field of low-frequency voltage metrology. We measured a linearity of ±6 μV (±0.6 μV/V full scale) over the 10 V range for such a DAC with a Zener voltage standard in use as its external 10 V reference. This result is a first step toward implementing such a DAC as an ac synthesized source, whose accuracy and stability could be established by a dc voltage standard reference¹.