We present a new record rms output voltage of 275 mV, which is a 25 % improvement over the maximum achieved with previous ac Josephson voltage standard (ACJVS) circuits. We demonstrate operating margins for these circuits and use them to measure the harmonic distortion of a commercial digitizer. Having exceeded the threshold of 125 mV rms for a single array of Josephson junctions, we propose and discuss the features of an eight-array circuit capable of achieving 1 V rms. We investigate the use of a resistive-divider to extend the ACJVS voltage accuracy to higher voltages. By use of a switched-input measurement technique, an integrating, sampling digital voltage meter, a resistive voltage divider, and ACJVS synthesized sine waves as reference voltages, we characterize the stability of a commercial calibration source for a few voltages up to 2.7 V.
IEEE Transactions on Instrumentation and Measurement
Digital-analog conversion, Josephson arrays, quantization, signal synthesis, standards, superconductor-normal-superconductor devices, voltage measurement