Josephson Sampler Response Using a Binary Search Algorithm

This article presents the use of a binary search algorithm to obtain the simulated response of a superconducting Josephson junction-based sampler. In the absence of noise, this simple approach is superior to mimicking the experimental approach of using an analog feedback circuit. This binary search method is first used to obtain the response of an idealized sampler, analyzing the sampler risetime to a step input and its dependence on damping. Next, it is applied to a full sampler circuit. Finally, we present the first experimental implementation of this method. A 10%-to-90% step-input response of 5.1 ps was obtained using 8 binary search iterations which yielded a current sensitivity of 1 mu A.