Millivolt calibrations using micropotentiometers with new disc resistors and planar MJTCS aided by new Millivolt amplifiers

New micropotentiometers (/spl mu/pots) have been built with planar multijunction thermal converters (PMJTC) on Si- and SiO/sub 2/-substrates, and with new disc resistors and redesigned housings. The step down from 100 mV to 2 mV can be performed with only two /spl mu/pots. New millivolt-amplifiers with gain factors of 11, 50, and 121 in conjunction with PMJTCs are developed to measure the output voltage of the /spl mu/pots down to 2 mV. Their high input impedance of >1 M/spl Omega/ /spl par/ < 6 pF avoids the loading of the output resistor of the /spl mu/pots. These systems lead to considerable reduction of the uncertainties in the millivolt-AC-DC transfer in the frequency range from 10 Hz up to 1 MHz.