Paper Info
Title
Modeling and Simulation of NAND Flash Memory Sensing Systems with Cell-to-Cell Vth Variations
Abstract
The sensing system in NAND flash memories is a complex mixed-signal circuit consisting of a large-scale cell array, wordline decoders, page buffers, analog/digital bit-counters, and digital sequence controllers. This paper proposes a model and simulation framework that can assess the effectiveness of various incremental/adaptive algorithms used by digital controllers for the read, program, and erase operations, while simulating the progression of individual cell threshold voltages (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) and modeling the detailed analog characteristics of the page buffers. The proposed model is written entirely in SystemVerilog, and its analog parts are described using the XMODEL primitives, which enable efficient and event-driven simulation of analog circuits. The proposed model can simulate a 40μs-long incremental step pulse programming (ISPP) sequence with the maximum loop iteration count of 4 on a 12K-bit block of single-level cells (SLC) in less than 2 minutes, and can assess the trade-offs between the programming speed and reliability as a function of the pulse step size and the impacts of the page buffer's sensing time on the final cell V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> distribution.
Year
DOI
Venue
2020
10.1145/3400302.3415769
2020 IEEE/ACM International Conference On Computer Aided Design (ICCAD)
Keywords
DocType
ISSN
NAND flash sensing system,mixed-signal circuit,cell threshold voltage distribution,XMODEL,SystemVerilog
Conference
1933-7760
Citations 
PageRank 
References 
0
0.34
5
Authors
2
Name
Order
Citations
PageRank
Nayoung Choi1414.24
Jaeha Kim238251.63