AC voltage converter module with thin-film Multijunction Thermal Converter

An ac module for a dc multimeter has been designed around the Planar Multijunction Thermal Converter (PMJTC) to measure ac voltage by automatic ac-dc transfer for frequencies from 10 Hz up to 1 MHz. The electronic uses the standard PMJTC in an isothermal way. It applies the sum of the ac signal and the dc feedback at the same time directly to one heater. The dc therefore is an accurate measure for the ac quantity. With this design the time for an accurate ac-dc transfer is reduced considerably.