Binary AC Josephson system and bias current circuits at NIM

This paper reports the progress of binary Josephson system for precise ac waveform synthesis in National Institute of Metrology, China (NIM). We designed a 32-channel bias source for dynamic voltage synthesis up to 1 kHz with a programmable Josephson junction array. The latest design of output drive current has a rise-time less than 50 ns on 100 ohm resistant. The 32-channel bias source is able to simultaneously provide bias current for two 1-volt SINIS junction arrays to synthesis two synchronous AC voltages.