Invention Grant
- Patent Title: Periodically updating a log likelihood ratio (LLR) table in a flash memory controller
-
Application No.: US14198862Application Date: 2014-03-06
-
Publication No.: US09916906B2Publication Date: 2018-03-13
- Inventor: Yunxiang Wu , Yu Cai , Zhengang Chen , Erich Haratsch
- Applicant: Seagate Technology LLC
- Applicant Address: US CA Cupertino
- Assignee: Seagate Technology LLC
- Current Assignee: Seagate Technology LLC
- Current Assignee Address: US CA Cupertino
- Agency: Smith Tempel Blaha LLC
- Agent Robert A. Blaha
- Main IPC: G11C7/14
- IPC: G11C7/14 ; G11C29/52 ; G11C29/04 ; G11C29/02 ; G11C16/34 ; G11C11/56 ; G06F11/10 ; G11C29/50

Abstract:
Log likelihood ration (LLR) values that are computed in a flash memory controller during read retries change over time as the number of program-and-erase cycles (PECs) that the flash memory die has been subjected to increases. Therefore, in cases where an LLR table is used to provide pre-defined, fixed LLR values to the error-correcting code (ECC) decoding logic of the controller, decoding success and the resulting BER will degrade over time as the number of PECs to which the die has been subjected increases. In accordance with embodiments, a storage system, a flash memory controller for use in the storage system and method are provided that periodically measure the LLR values and update the LLR table with new LLR values. Periodically measuring the LLR values and updating the LLR table with new LLR values ensures high decoding success and a low BER over the life of the flash memory die.
Public/Granted literature
- US20150242268A1 PERIODICALLY UPDATING A LOG LIKELIHOOD RATIO (LLR) TABLE IN A FLASH MEMORY CONTROLLER Public/Granted day:2015-08-27
Information query