Low-voltage AC-DC transfer standards at NMIJ

Calibration methods for low-voltage ac-dc transfer standards below 100 mV are described. Aiming to provide high-accuracy calibration services in Japan, we have developed micropotentiometers (μpots) and resistive voltage dividers (RVDs). Low-voltage ac-dc transfer calibrations of a commercially available thermal transfer standard with amplifiers (TTS) at NMIJ were performed using both the μpots and RVDs. The results of the two methods are in good agreement. One of the advantages of using RVDs is that the ac-dc transfer differences can be determined by the same procedures as ordinary comparison measurements.