Architecture
50-variable 3-SAT solver in TSMC 28nm. Accepts problems directly without preprocessing. Each variable maps to a relaxation oscillator spin; clauses are NOR3 gates in a feedback network. Twin analog/digital crossbars provide unrestricted all-to-all 3-SAT connectivity, so any variable can appear in any clause without decomposition. When a clause is unsatisfied, current injection rotates spins toward a satisfying assignment. When all clauses are satisfied, the system freezes at a solution.
Dynamic Continuous-Time Injection
Spin oscillation activates only when feedback is present. This cuts solution time 6× and energy 8× versus continuously oscillating nodes, and removes the need for sampling circuitry: spins simply freeze at the final solution.
Results
Tested on all 1,000 problems in the 20-variable and 50-variable SATLIB benchmarks, 100 runs each, with 100% solvability. 1.6 µs for 20-variable problems, 31.7 µs for 50-variable. 3,000× faster and 14,000× more energy-efficient than WalkSAT on an AMD Threadripper. 0.58 mm².