Modeling and Simulation of Bi-SQUIDs and SQIFs Using InductEX-LVS and JoSIM

A bi-SQUID consisting of three Josephson junctions has been shown to provide improved linearity in the voltage-flux response when compared with conventional two junction dc SQUIDs. It had also been demonstrated that this improved linearity extends to SQUID arrays and SQIFs constructed using bi-SQUIDs. Experimental results for these arrays have typically been compared with results obtained from mathematical modelling since the manual creation of a complete model that can be simulated for each design is prohibitively time consuming and complex. We present a method of simulating such designs using superconducting EDA tools. Complete circuit models are obtained using the compact model extraction tool included in InductEx-LVS. These models include the Josephson junctions, inductors, resistors and all magnetic couplings from the layout. The models are simulated using JoSIM Superconductor Circuit Simulator to obtain the voltage-flux response. We discuss how the results compare with simulated results for designs that use conventional dc SQUIDs as well as with experimentally verified bi-SQUID designs from literature. Additionally, we consider the advantages and disadvantages of different flux bias application methods for 2D bi-SQUID SQIF designs.