Determination of the Bit Error Rate Due to Thermal Noise Using JoSIM Superconducting Circuit Simulator and the Monte Carlo Method

• Published in: IEEE transactions on applied superconductivity Vol. 33; no. 5; pp. 1 - 5
• Main Authors: Hall, Tessa, Delport, Johannes A., Fourie, Coenrad J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bit error rate; Circuit Design; Electronic Design Automation; Integrated circuit modeling; Junctions; Libraries; Monte Carlo methods; Monte Carlo simulation; Resistors; RSFQ; Simulation; Simulation Software; Simulators; Superconductivity; Thermal noise
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2023.3251940

Thermal noise requires careful consideration during the design process of RSFQ circuits since it reduces circuit operating margins and can cause switching errors. Bit error rate (BER) provides a useful means of analysing the effect of this noise on a circuit. With tools developed under the IARPA SuperTools project, we present an implementation of the Monte-Carlo technique for determining BER via simulation. The Monte-Carlo method has been considered previously but not widely implemented due to slow simulation times preventing the determination of small BER values. We use JoSIM - an efficient simulator with SPICE syntax that allows for the simulation of superconducting components and noise sources with improved speed over older superconductor simulators. This speed improvement makes the Monte-Carlo method viable. The simulated BER is plotted against bias current with values in the low-BER region interpolated from the simulated values using MATLAB. We show how the results need to be used as a further qualifier of circuit performance for the characterization of a logic cell library.