Eye-diagram and scattering parameter characterization of superconducting and gold coplanar transmission lines

We report the gigahertz experimental results of time and frequency performance on YBCO high-temperature superconductor and gold coplanar transmission lines. An on-wafer direct probing measurement system was used to collect data at cryogenic temperatures on both YBCO and gold coplanar lines. The insertion loss of the 6 cm lines at a frequency of 2.5 GHz was measured to be -0.03 dB for the superconducting line compared to -10.4 dB for the gold line at 80 K. Eye-diagram measurements were performed on the packaged lines and show the correlation between the insertion loss of the line and the attenuation of a pseudorandom bit sequence. The measured eye height was 170 mV for the YBCO compared to 90 mV for a gold line at 1 Gbit/s and a temperature of 77 K for the packaged 6 cm lines.