Ising machine based on charge re-distribution
Yongchao Liu, L. C. Sun, Matthew Burns, Michael C.Y. Huang, Hui Xiang Wu · 2025
Ising machines have attracted significant attention for solving quadratic unconstrained binary optimization (QUBO) with high performance. Among them, CMOS-compatible dynamics-based designs are promising approaches with high efficiency, scalability, and potential extension to more general combinatorial optimization problems (COPs) beyond QUBO problems. However, these machines can be limited by poor solution quality due to variations and leakage, or by long solution times resulting from inefficient annealing. In this paper, we propose a novel all-to-all connected Ising machine based on charge redistribution, capable of solving generic QUBO problems. To enhance solution quality, we apply a stochastic cycling annealing technique. A 50-spin Ising machine was developed using commercial 65nm CMOS technology, with both system-level and circuit-level designs implemented. Additionally, behavior-level simulations were conducted to evaluate the performance of a larger system. Simulation results show that the proposed Ising machine delivers competitive solution quality with reduced time-to-solution, making it a strong candidate for solving COPs.