Interface circuit using JTLs as control lines of SQUID array

Interface circuits for the RSFQ circuit system were designed, fabricated and their frequency characteristics were investigated. Key elements of the interface circuit were the series array of SQUIDs and a JTL as a control line of the SQUID. The interface circuit was designed to cover the operating frequencies much greater than 10 GHz. A high-frequency signal generator circuit consisting of a ring oscillator, a frequency divider, and an interface circuit was fabricated. High frequency signals produced in the ring oscillator could be detected by using the interface circuit. The h/2e relationship between the oscillation frequency and the ac Josephson voltage was verified.