Design of wideband superconducting coplanar delay lines

A novel superconducting delay line is presented, it is formed from a coplanar transmission line, the transmission line has a meander structure, which is then curled into a double spiral to maximise the use of the substrate area. Full-wave simulations are conducted on a 0.5 m coplanar line of this type and also a conventional double-spiral line for comparison. Geometric factors limiting the achievable bandwidth are addressed. To extract the device delay and loss without incurring the problems of the input and output connections, AC coupled measurements are done using a 25 ns delay line as a resonator. Quality factors of the resonances from 20 MHz to 20 GHz are measured. The estimated group delay of the delay line is given.