Single flux quantum signal transmission techniques in building practical RSFQ circuits

The practical implementation of rapid single flux quantum (RSFQ) technology requires much more complexity than the presently developed circuits. Multiple chips have to be integrated with a technology that is reliable at cryogenic temperatures. The interchip and intrachip data transmission speed of tens of GHz has to be supported. Also, the large RSFQ circuits need serial biasing to reduce the amount of the bias current. The test circuits were designed, simulated, fabricated with Nb technology, and tested at a temperature of 4.2 K. Test results at GHz frequencies showed that SFQ pulses can be successfully transmitted over an extensive distance in a chip, between chips, and over the circuits in different round planes. (C) 2003 Elsevier Ltd. All rights reserved.