Design Framework for Ising Machines with Bistable Latch-Based Spins and All-to-All Resistive Coupling

Memristive crossbars have been proposed as a promising pathway to enabling all-to-all connections for a variety of applications. One such application is the latch-based dynamical Ising machine, which have been proposed for solving combinatorial optimization problems. However, the impact of the design of the memristive crossbar on the performance of the latch-based Ising machine remains unclear. We present a SPICE-level model and simulation framework for analyzing and evaluating the latch-based dynamical Ising machine that use memristive crossbars to achieve all-to-all coupling between Ising spins implemented as latches. Our design space exploration reveals that the solution quality is highly sensitive to the circuit and device design parameters and sizes of the problems. An effective metric that can capture the effect of several design parameters on the statistical results is then proposed to quantify the system functionality. Finally, optimization techniques based on our proposed metric that models the effect of several design parameters on the solution quality of the Ising machine are proposed and demonstrated on MaxCut solving. Our evaluation results on a 128×128 crossbar array-based design show >98% solution quality across a wide range of problem sizes is achievable.