Tutorial 5
Signal integrity Engineering With Superconductors: An Introduction

Patrick J. Zabinski , Mayo Clinic

Superconductors are intriguing to signal integrity engineers. In contrast to normal conductors like copper that have resistance and thus both attenuation and dispersion, the zero resistance of superconducting interconnect often leads to visions of tremendous bandwidths over infinite physical distances. Superconductors are correspondingly finding their way into high-speed data links.

While it is relatively easy to model the zero-resistance behavior of superconductors, doing so neglects unique properties of superconductors that directly impact signal integrity. In particular, a parameter unique to superconductors known as kinetic inductance affects characteristic impedance, propagation velocity, and crosstalk. Similarly, neglecting critical operating parameters such as temperature, field strength, and current can lead to disastrous results.

Aimed at preparing engineers to analyze superconducting links, this tutorial introduces superconductors from the eyes of signal integrity engineers. It begins with an overview of the electrical behavior of superconductors and their critical operating parameters. Kinetic inductance and the associated London penetration depth are then introduced, followed by a selection of data link simulations to demonstrate the uniqueness of superconducting interconnect.

Being targeted at practicing SI engineers, the tutorial omits the underlying physics of superconductors that are well covered in numerous textbooks. Prior experience with superconductors is unnecessary, but a general understanding of signal integrity is helpful.

Patrick J. Zabinski (BSEE, MSEE, MBA) started his career in 1989 at the Special Circuits group at Unisys in Eagan, Minnesota, developing high speed digital fiber optic links. He joined the Special Purpose Processor Development Group at the Mayo Clinic in Rochester, Minnesota, in 1990 where he analyses, designs, and advances high-performance packaging, semiconductor technologies, and systems. Leveraging a foundation of three decades of signal-integrity experience, Pat has been analyzing the signal integrity of superconducting interconnect for nearly a decade and has led teams through the advancement and application of related tools, theories, and capabilities.