忆阻器阻变随机存取存储器及其在信息存储中的应用
摘要
Recently acclaimed the fourth fundamental circuit element, the memristor was theoretically predicted by Leon Chua in 1971, although its single device electronic implementation eluded the attention of integrated circuit designers for the past three decades and was first reported in 2008 by the Hewlett-Packard (HP) Laboratory researchers while developing crossbar-based ultra high-density nonvolatile memories. Memristor-based hybrid nanoscale CMOS technology is expected not only to impact the flash memory industries profoundly, but also to revolutionize digital and neuromorphic computing. The memristor exhibits a dynamical resistance state that depends on its excitation history and which can be exploited to build transistor-less nonvolatile semiconductor memory (NVSM), commonly known as resistive RAM (RRAM). This paper addresses an implementation scheme for memristor-based resistive random access memory (MRRAM), a nano-scale binary memory that is compatible with modern computer systems. Its structure is similar to that of static random access memory (SRAM), but with the memristor replacing the underlying RS flip-flop. By improving the MRRAM, we propose a multilevel memory with greater data density, which stores multiple bit information in gray-scale form in a memory unit. Reported computer simulations and numerical analyses verify the effectiveness of the proposed scheme in storing ASCII characters and gray-scale images in binary format.