Static information storage and retrieval – Read/write circuit – Testing
Reexamination Certificate
2007-08-07
2007-08-07
Ho, Hoai V. (Department: 2827)
Static information storage and retrieval
Read/write circuit
Testing
C365S185180, C365S185210
Reexamination Certificate
active
11332567
ABSTRACT:
A flash memory device of the multi-level cell (MLC) type, in which control gate voltages in read and programming operations and a bandgap reference voltage source are trimmable from external terminals, is disclosed. In a special test mode, control gate voltages can be applied to a selected programmed memory cell so that the threshold voltage of the cell can be sensed. A digital-to-analog converter (DAC) use for programming and a second read/verify DAC apply varying analog voltages and are sequentially used to verify the programming of an associated set of memory cells in this special test mode, with the DAC input values that provide the closest result selected for use in normal operation. These DAC's are dependent on the value of a reference source that my also be trimmed.
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Chen Jian
Lutze Jeffrey
Tu Loc
Wan Jun
Anderson Levine & Lintel
Ho Hoai V.
SanDisk Corporation
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