MULTILAYER EDGE SNS SQUIDS FOR DIGITAL CIRCUITS

We have fabricated and characterized direct-injection High Temperature Superconducting (HTS) SQUIDs using a six-epitaxial-layer process whic h integrates edge geometry superconductor-normal-superconductor (SNS) junctions with an HTS ground plane. The period of the SQUID threshold curves was used to infer microstrip inductances of approximately 1 pH/ square at 65 K. Total SQUID inductances as low as approximate to 5 pH were inferred from the measured critical current modulation depth. A n ovel junction geometry was used in some devices to reduce the parasiti c inductances of the junction leads by approximately 1 pH. Maintaining such low inductances is particularly important for Single Flux Quantu m digital circuits.