Single flux quantum comparators for HTS AD converters

We have investigated different comparators for Flash and Sigma-Delta high temperature superconducting ADCs designed using three-layer HTS tri-crystal junction integrated circuit technology with spread of the junction critical currents less than 10% and features size 0.6 mu m. Using the theoretical estimations for the bit error rate in RSFQ circuit under the restrictions of the given technology, we have estimated working temperature as T = 62 K. At this temperature, the circuits were optimized in order to achieve maximum performance of the related ADCs in terms of input bandwidth, resolution and operating margins. For design purposes, a novel method was developed for inductance calculation with 3D magnetic field distribution in multilayer superconducting technology and extraction of the inductance matrix of the equivalent circuit. (C) 1999 Elsevier Science B.V. All rights reserved.