A fully automated digital AC/DC transfer standard

The design of a microprocessor-based ac/dc transfer standard is described. A differential multijunction thermal converter (DMJTC) is used as the transfer element. Improved design of the attenuator and peripheral electronics around the DMJTC allows measurements of rms voltage 0.1 to 1000 V over the frequency range dc to 1 MHz. The microprocessor provides software compensation for ac/dc transfer error as a function of frequency. Accuracy is in the order of 20 to 500 ppm, depending on voltage and frequency.