HYBRID INTEGRATION OF MICROWAVE-OSCILLATORS WITH JOSEPHSON SERIES ARRAYS FOR THE USE AS VOLTAGE STANDARDS

We have designed and fabricated a new type of Josephson device to be h ybrid integrated with microstripline oscillators. For optimum matching of the Josephson Series array to the oscillator the samples make use of a new stripline design. The first circuits were fabricated in a sim plified Nb/Al2O3/Nb technology and exhibit excellent de characteristic s and good microwave coupling to the junctions of the array. At 70 GHz constant voltage steps up to 350 mV could be observed. By hybrid inte grating different samples with a new 10-GHz oscillator, constant volta ge steps were created. For this experiment the Josephson current densi ty had to be low enough to reduce the plasma frequency of the junction s to well below the driving frequency.