Sequential Circuits Synthesis for Rapid Single Flux Quantum Logic Based on Finite State Machine Decomposition

TL;DR

This paper introduces a novel FSM decomposition-based sequential circuit synthesis algorithm tailored for RSFQ logic, enhancing large-scale circuit design efficiency and performance.

Contribution

The paper presents a new synthesis algorithm for RSFQ sequential circuits using FSM decomposition, addressing challenges with feedback loops and non-linear blocks.

Findings

Successfully synthesizes large-scale sequential circuits

Demonstrates improved circuit performance and reduced costs

Effective handling of feedback logic in RSFQ circuits

Abstract

Rapid Single Flux Quantum (RSFQ) logic is a promising technology to supersede Complementary metal-oxide-semiconductor (CMOS) logic in some specialized areas due to providing ultra-fast and energy-efficient circuits. To realize a large-scale integration design, electronic design automation (EDA) tools specialized for RSFQ logic are required due to the divergences in logic type, timing constraints, and circuit structure compared with CMOS logic. Logic synthesis is crucial in converting behavioral circuit description into circuit netlist, typically combining combinational and sequential circuit synthesis. For the RSFQ logic, the sequential circuit synthesis is challenging, especially for non-linear sequential blocks with feedback loops. Thus, this paper presents a sequential circuit synthesis algorithm based on finite state machine (FSM) decomposition, which ensures design functionality, lowers costs, and improves the RSFQ circuit performance. Additionally, we present the synthesis processes of the feedback logic and the 2-bit counter to demonstrate how the proposed algorithm operates, and ISCAS89 benchmark circuits reveal our method's ability to synthesize large-scale sequential circuits.