Low-Frequency Characterization in Thermal Converters Using AC-Programmable Josephson Voltage Standard System

We have measured the low-frequency characteristics of thermal voltage converters down to 1 Hz using a differential sampling measurement system based on ac-programmable Josephson voltage standard (AC-PJVS) system. The measured ac-dc transfer difference of a planar multijunction thermal converter using our system is evaluated to be < 1 mu V/V above 10 Hz and < 35 mu V/V at 1 Hz with lower uncertainties compared to the conventional method. The estimated overall uncertainty measured by using our system is 3.1 mu V/V (k = 1) at the frequency of 10 Hz and root-mean-square voltage of 3 V. Our measurement results above 10 Hz are in good agreement with the results obtained by the conventional method within a standard deviation of the mean. Our differential sampling measurement system using AC-PJVS is a useful tool for low-frequency ac voltage metrology.