Fig. 6

(a) Measurement waveforms of a JTL test circuit at 100 kHz in liquid helium. The input signal (high voltage: logic 1; low voltage: logic 0) is applied to the DC/SFQ converter, where an SFQ pulse is generated at the rise edge of the input signal. The output signal is observed by the SFQ/DC converter, where each rise or fall edge indicates a logic 1. The output signal was amplified by a room-temperature amplifier with a 40-dB gain. (b) Measurement results of operating bias margins, which are normalized to a bias voltage of 0.8 mV.