An electronic device that includes a first programmable metallization cell
(PMC) that includes an active electrode; an inert electrode; and a solid
electrolyte layer disposed between the active electrode and the inert
electrode; and a second PMC that includes an active electrode; an inert
electrode; and a solid electrolyte layer disposed between the active
electrode and the inert electrode, wherein the first and second PMCs are
electrically connected in anti-parallel.