Stepwise controlled voltage sensing scheme for high-density ReRAM with multi level cell

Abstract

In this paper, we study basic read methods of cross-point ReRAM which is a promising next generation memory. Based on this study, we propose a novel sensing method for Multi-Level ReRAM Cell without area penalty or read time degradation. By applying an increasing stepwise voltage to the gate of the nMOS switch that connects the sense amplifier with the cell array, the level of charge sharing between these two elements can be adjusted to a desired level. The proposed scheme achieves linear increase in reading time according cell resistance instead of the exponential in the conventional method. As a result, the reading time is improved by about twice as compared with the conventional method with applying the constant voltage.