Using STT-RAM Based Buffers in Digital Circuits

STT-RAMs are good candidates to replace conventional SRAM cache and DRAM in main memory, but their applicability in digital logic circuits is unclear. Our experiments explore the power benefit of utilizing nonvolatile buffers in digital circuits, with a case study of Ripple Carry Adder and Carry-Skip Adder circuits. We design a low-overhead 2T1MTJ buffer and place it in the intermediate non-critical paths that hold data for long times. Use of NVMs in these paths allows us to turn off parts of the adder to save power. Our simulations show 22.4% and 10.8% power saving in 512-bit RCA and SCA structures respectively with minimal area overheads.