US 11,853,590 B2
Read threshold estimation system using calculations based on polynomial regression
Meysam Asadi, Fremont, CA (US); Teodor Vlasov, Minsk (BY); Fan Zhang, Fremont, CA (US); and Aman Bhatia, Los Gatos, CA (US)
Assigned to SK hynix Inc., Gyeonggi-do (KR)
Filed by SK hynix Inc., Gyeonggi-do (KR)
Filed on Dec. 2, 2021, as Appl. No. 17/541,039.
Prior Publication US 2023/0176768 A1, Jun. 8, 2023
Int. Cl. G06F 12/00 (2006.01); G06F 3/06 (2006.01); G11C 11/56 (2006.01); G11C 16/26 (2006.01); G11C 16/04 (2006.01)
CPC G06F 3/0655 (2013.01) [G06F 3/0604 (2013.01); G06F 3/0679 (2013.01); G11C 11/5642 (2013.01); G11C 11/5671 (2013.01); G11C 16/0483 (2013.01); G11C 16/26 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A memory system comprising:
a memory device including a plurality of pages; and
a controller configured to:
perform read operations on a select page among the plurality of pages using a plurality of read threshold voltages;
determine, for each read operation, a mathematical model by using a) a set function of a read threshold voltage set among the plurality of read threshold voltages and b) a set checksum value;
determine a polynomial regression model based on the mathematical model;
determine a parameter set by using multiple computations between input and output matrices based on the polynomial regression model; and estimate a next read threshold voltage for a next read operation based on the parameter set,
wherein the input matrix includes entries of read threshold voltage sets from the read operations and the output matrix includes entries of check sum values for the read operations,
wherein the multiple computations correspond to a product between a first component and a second component, the first component being the inverse of a third component, the second component being a product between the transpose of the input matrix and the output matrix, the third component being a product between the transpose of the input matrix and the input matrix,
wherein each component is calculated by a mathematical operation on two or more numbers as entries selected from one or more among the input and output matrices, and
wherein the mathematical operation includes normalizing and scaling down the two or more numbers for multiplication, division, and multiplication followed by division.