Superconductive single-flux-quantum (SFQ) circuits are well-suited for integrated circuits in stochastic computing, where signals are represented by the probability of a “1” appearing in a finite-length binary sequence. This suitability arises from their high-speed operation and the inherent ease of the stochastic behavior.
In stochastic computation, the correlation between binary number sequences (stochastic numbers, SNs) representing signals degrades computational accuracy. Large-scale arithmetic circuits require large fan-out signal splitters. However, due to the correlation problem, an SN cannot simply be split using a single-flux quantum (SFQ) splitter.
In this study, we propose a novel SN splitter that leverages frequency synchronization between parallelized superconductive random number generators (SRNGs). In an n-output SN splitter, the probability of a “1” appearing in the input SN is replicated across n SRNGs via frequency synchronization in the SFQ circuit. These SRNGs generate random number sequences that maintain the same probability of “1” occurrence as the input SN. Since the parallelized SRNGs produce mutually uncorrelated random outputs, the proposed SN splitter effectively mitigates the accuracy degradation caused by correlation between SNs.
We designed, implemented, and tested a 4-output SN splitter using a 10 kA/cm^2 Nb process. The high-speed operation of the SN splitter was successfully demonstrated at frequencies up to 30.3 GHz. In the presentation, we