Flexible Routing to Overcome the Embedding Bottleneck of Oscillator-based Ising Machines.

The demand for computing power is steadily increasing. The time and energy per computation need to be reduced. The emerging class of Ising machines has the potential to compute such optimization problems faster and more energy efficient. Oscillator-based Ising Machines (OIMs) utilize a network of coupled complementary metal–oxide–semiconductor (CMOS) oscillators. They represent the optimization problem in their configurable hardware and exploit the oscillator interaction for computation. Thus, the optimization problem must be mapped to the available hardware resources first. A high hardware connectivity simplifies this problem embedding but increases the silicon area. To overcome the trade-off, we propose reconfigurable connections similar to field programmable gate arrays (FPGAs). Since the oscillator coupling is fundamentally different from CMOS logic, special requirements must be considered. This work analyzes the unique behavior of such routable connections for oscillator coupling and proposes a delay compensation technique to enable flexible routing channels in OIMs.