Vierra Magen Marcus & DeNiro LLP
Complete word line look ahead with efficient data latch assignment in non-volatile memory read operations
Shifts in the apparent charge stored by a charge storage region such as a floating gate in a non-volatile memory cell can occur because of electrical field coupling based on charge stored by adjacent cells. To account for the shift, compensations are applied when reading. When reading a selected word line, the adjacent word line is read first and the data stored in a set of data latches for each bit line. One latch for each bit line stores an indication that the data is from the adjacent word line. The selected word line is then read with compensations based on the different states of the cells on the adjacent word line. Each sense module uses the data from the adjacent word line to select the results of sensing with the appropriate compensation for its bit line. The data from the adjacent word line is overwritten with data from the selected word line at the appropriate time and the indication updated to reflect that the latches store data from the selected word line. The efficient use of the data latches eliminates the need for separate latches to store data from the adjacent word line.
SanDisk Corporation
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Man Lung Seungpil
Mui Lee