Progress on AC Voltage Measurement System with Josephson Voltage Standard

This paper describes the new progress on ac voltage measurement system with Josephson voltage standard at NIM. A low-noise differential voltage preamplifier is placed in front of a single-ended sampling ADC in order to increase common-mode rejection and minimize interference from ground loop currents, and a new type of sine fit algorithm is used to enhance the data processing accuracy and reliability of the differential sampling system. The experimental results show the feasibility of current system.