SAT Encoding-based Verification of Sneak Path Problem in Via-switch FPGA

FPGA that introduces via-switches, a kind of non-volatile resistive RAMs, for crossbar implementation is drawing attention due to higher integration density and performance. However, programming those switches arbitrarily in a crossbar is not trivial since a programming voltage must be given through signal wires that are shared by multiple via-switches. Consequently, depending on the previous programming status, unintentional switch programming may occur due to signal detour, which is called sneak path problem. This paper encodes programming operations in via-switch based crossbar into a satisfiability problem and rigidly verifies the sneak path problem. Verification results show that sneak path problems can be solved by imposing a specific programming constraint.