06952365 is referenced by 107 patents and cites 26 patents.

Storage elements are read multiple times and the results are accumulated and averaged for each storage element to reduce the effects of noise or other transients in the storage elements and associated circuits that may adversely affect the quality of the read. Several techniques may be employed, including: A full read and transfer of the data from the storage device to the controller device for each iteration, with averaging performed by the controller; a full read of the data for each iteration, with the averaging performed by the storage device, and no transfer to the controller until the final results are obtained; one full read followed by a number of faster re-reads exploiting the already established state information to avoid a full read, followed by an intelligent algorithm to guide the state at which the storage element is sensed. These techniques may be used as the normal mode of operation, or invoked upon exception condition, depending on the system characteristics. A similar form of signal averaging may be employed during the verify phase of programming. An embodiment of this technique would use a peak-detection scheme. In this scenario, several verify checks are performed at the state prior to deciding if the storage element has reached the target state. If some predetermined portion of the verifies fail, the storage element receives additional programming. These techniques allow the system to store more states per storage element in the presence of various sources of noise.

Title
Reducing the effects of noise in non-volatile memories through multiple reads
Application Number
10/799416
Publication Number
6952365 (B2)
Application Date
March 12, 2004
Publication Date
October 4, 2005
Inventor
Daniel C Guterman
Fremont
CA, US
Carlos J Gonzalez
Los Gatos
CA, US
Agent
Parsons Hsue & de Runtz
Assignee
SanDisk Corporation
CA, US
IPC
G11C 011/34
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