A non-volatile microcontroller with integrated floating-gate transistors

Wing-Kei S. Yu, Shantanu Rajwade, Sung-En Wang, Bob Lian, G. Edward Suh, Edwin Kan

Abstract: We present a non-volatile processor architecture where its entire state can be almost instantly stored and restored in a non-volatile fashion. This capability is attractive for embedded or mobile devices in highly energy constrained environments. The non-volatile microprocessor can enable long computations to continue across power interruptions on self-powered devices or save idle power consumption without sacrificing responsiveness. To realize this vision, a microprocessor must be able to copy state between volatile and non-volatile storage with minimal latency and energy consumption. Our non-volatile architecture addresses this challenge through a per-cell integration of floating-gate non-volatile transistors into volatile state elements and careful system-level optimizations to hide expensive non-volatile operations. We evaluate this approach with a transistor-level prototype of an 8-bit nonvolatile microcontroller. Experiments indicate that the proposed architecture has minimal impact on normal operation while enabling all processor state to be preserved across an unexpected power interruption.