Bit error rate measurement of a measuring system designed for superconducting digital circuits

We hair developed a measuring system for high-T-C, superconducting single-f lux quantum circuits and evaluated its performance in terms of bit error ra te (BER) measurement for given signal voltage levels. The system includes m agnetic shields and a high-frequency tc st fixture mounted on a closed-cycl e cooler. The test fixture is made of non-magnetic material. The transmissi on characteristics of the measuring system were evaluated by using a vector network analyzer at frequencies ranging from 40 MHz to 20 GHz. The operati ng temperature of the measuring system ranges from 20 K to room temperature . We connected a 12-GHz wideband pulse amplifier to the system and evaluate d its high-speed transmission characteristics. We used a standard 50-Omega microstrip line as an impedance-matched sample. The signal used ill the exp eriment was a 2(15) - 1 pseudo random bit signal (PRBS) at 3Gbps. As: a res ult. the output voltage required fur an output driver under the experimenta l condition was 18.8 mV in order tu obtain a resolution of BER measurement of 10(-12).