AC JOSEPHSON VOLTAGE STANDARD - PROGRESS REPORT

Progress toward a Josephson voltage standard for fast de measurements and accurate ac waveform synthesis is described, A superconductor-norm al-superconductor (SNS) junction process is used to make 5 mA critical current arrays with up to 32 768 junctions, With rf excitation at 11 GHz these arrays generate milliampere constant-voltage steps, A bias c ontrol circuit that provides output current amplification, transient s uppression, and submicrosecond settling time is used with both superco nductor-insulator-superconductor (SIS) and SNS junction arrays for fas t, automated measurements of A/D converter linearity, a test for subna novolt accuracy, waveform synthesis, and a preliminary measurement of the ac-dc difference of a thermal voltage converter.