Bit error rate measurement of a high-speed small-voltage signal using a superconducting transmission line

We developed a measuring system that has a magnetically shielded wide-band test fixture mounted on a closed-cycle cryo-cooler, and used this system to investigate the feasibility of cryo-packaging technology for high-Tc superconducting digital electronics. In this work, we evaluated the bit-error-rate (BER) performance of a system in which was installed a 50-/spl Omega/ standard microstrip line (MSTL) and a YBa/sub 2/Cu/sub 3/Ox microstrip line to a coplanar waveguide (CPW) transmission line converter (MCC). In the experiment, we used 3-Gbps, 2/sup 15/-1 pseudo-random binary sequence (PRBS) signals. The temperature of the test fixture was 20 K. Results showed that the BER was 3.74/spl times/10/sup -9/ for the 50-/spl Omega/ MSTL when the signal amplitude at the sample was 13.3 mV, and 1.52/spl times/10/sup -9/ for the MCC when the amplitude was 30.8 mV. The effect of the signal loss and impedance mismatch on the BER is also discussed.