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-Ω standard microstrip line (MSTL) and a YBa₂ Cu₃Ox microstrip line to a coplanar waveguide (CPW) transmission line converter (MCC). In the experiment, we used 3-Gbps, 2 ¹⁵-1 pseudo-random binary sequence (PRBS) signals. The temperature of the test fixture was 20 K. Results showed that the BER was 3.74×10^-9 for the 50-Ω MSTL when the signal amplitude at the sample was 13.3 mV, and 1.52×10^-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