基于一种NAND闪存页缓存器设计的C/F读取算法研究

为减小共源线噪声对NAND闪存读可靠性的影响，设计了一种可实现C/F（Coarse/Fine）读取操作的页缓存器电路，并设计实现了适用于此电路的C/F读取算法，显著减小了共源线噪声.该算法通过两次子读感应读取存储单元，在第一次子读感应中分辨出阈值电压较低的存储单元并标记在页缓存器中，使其不再进行第二次子读感应，从而减小共源线噪声引起的阈值偏移.电路仿真计算表明，该支持C/F读取算法的页缓存器结构能够减小阈值偏移至少495.6mV，有效提高了NAND闪存读操作的精确性.

Research on Coarse/Fine Read Algorithm Based on a NAND Flash Page Buffer Design

To reduce the effect of the common source line noise in read operation of NAND Flash Memory,a page buffer circuit which can realize the coarse/fine read operation is proposed and a C/F read algorithm suitable for the page buffer circuit is introduced and implemented which can reduce the common source line noise significantly.There are two sub-read operations in the algorithm,the purpose of the first sub-read operation is to distinguish the cells with lower threshold voltage and mark them in page buffer circuit.These cells are no longer sensed in the second sub-read operation.As a result,the threshold voltage shift caused by the common source line noise is suppressed.The circuit simulation results show that the page buffer structure which supports the C/F read algorithm can reduce the shift of the threshold distribution more than 495.6mV and the read accuracy of NAND Flash Memory is greatly improved.