Micropotentiometers Providing Low Output Impedance for Millivolt AC–DC Transfer

Millivolt ac-dc transfer devices and ac measuring instruments are calibrated with new micropotentiometers (mupots) with low output impedance. Newly designed output resistors of 0.2 and 0.1 Omega lead to reduced load corrections for 150 kOmega input impedance amplifiers of only a few muV/V. The higher current required is measured at 1 MHz with a 500 mA thermal current converter. At 1 MHz, expanded uncertainties (k = 2) less than 40 muV/V are achieved from 100 down to 10 mV