Differential-sampling control algorithm and theoretical analysis for programmable-Josephson-voltage-standard traceability application

The programmable Josephson voltage standard (PJVS) provides a new way and higher accuracy for the traceability of traditional measurement standards. To improve the applicability and reduce the uncertainty of the PJVS, a PJVS-based analog-to-digital converter (ADC) scheme for the alternating-current (AC) voltage measurement is proposed and the theoretical error model is derived based on discrete Fourier transform. The influence of the amplitude and phase error of the AC voltage is simulated; an adaptive differential-sampling control algorithm is proposed to control the relative amplitude and phase between the AC voltage and PJVS voltage, improving the error of the PJVS-based ADC. Furthermore, the authors obtained the exponential decay algorithm error curve that varies with phase error and the M-shaped variation curve with sampling error by simulation and a PJVS-based ADC with different sampling DVM, which provides possibilities for optimizing the measurement error of the PJVS-based ADC.