High-T/sub c/ superconducting coupled coplanar transmission lines: a 3D-transmission line matrix analysis

The application of the three-dimensional transmission line matrix (3-D-TLM) approach to straight high-T/sub c/ superconducting coupled coplanar waveguide (CCPW) structures, suitable for high-speed interconnects, is presented. The authors have investigated CCPWs fabricated from laser ablated YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin-films on lanthanum aluminate (LaAlO/sub 2/) substrates with 0.5-mm thickness. To represent three-dimensional space, the symmetrical condensed TLM node and a nonuniform discretization scheme are used. The surface impedance of the high-T/sub c/ superconducting film is described by London theory and modeled as a thin TLM network loaded with resistive and inductive stubs. The losses of the substrate are represented by additional conductances connected in parallel. CCPW line-to-line coupling is evaluated. Preliminary experimental results with gold CCPWs on LaAlO/sub 3/ are discussed.<>