Development of an optimization tool for single flux quantum based analog and digital circuits

Discovery of superconductor electronics has enabled the design of low power consumption digital circuits and so sensitive sensor readout circuits that cannot be achieved by using semiconductor technology. However, there is no existing optimization tool that takes thermal noise and fabrication tolerances into account for analog and digital circuits. In this work, an analog circuit optimization tool that considers thermal noise has been generated. Then, one bit comparator Quasi One-junction SQUID (Superconductor QUantum Interference Device) circuits are optimized using this tool and the results are experimentally proved. The parameter tolerances, occurs during the fabrication of superconductor SFQ (Single Flux Quantum) digital circuits, cause the variations in the delay time of digital cells, even not to operate of the cells. If these fabrication tolerances are not considered when designing SFQ digital circuits, they bring about malfunction of the circuits. When the fabrication induced tolerances are taken into account, timing margins are kept large. Thus, maximum operating frequencies of the circuits are highly limited. In this work, a digital optimization tool has also been created that mitigates variations in the delays of digital cells by maximizing the yield rates and RSFQ (Rapid Single Flux Quantum) digital circuit library has been optimized. A particle swarm optimization algorithm, has ability to converge rapidly and easy to implement, has been used for both analog and digital circuits optimizations and a number of modifications have been done in order to speed up the converging time. Keywords: Superconductor, SQUID, RSFQ, QOS, Optimization, PSO