Page mode floating gate memory device storing multiple bits per cell
US5754469A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | Oct 1, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/5642
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An array (10) of multi-level floating gate memory cells includes wordlines (18) connected to memory cells along a row in the array, and bit lines (12) connected to memory cells along a column in the array. A wordline voltage source (27) is included which supplies selectively wordline voltages corresponding to respective threshold voltages of the memory cells in the array. A plurality of bit latches form a page buffer (11). Bit latches are coupled to corresponding bit lines, and have a first state and a second state. The bit latches include circuits (213-216) to change the bit latches from the first state to the second state in response to signals on the corresponding bit lines that are generated in response to a wordline voltage on a selected wordline being greater than or equal to the threshold voltage of a memory cell on the corresponding bit line connected to the selected wordline. Logic (21) controls the wordline voltage source and the bit latches to apply in a sequence the wordline voltages, and to sense the state of the bit latches after applying each wordline voltage in the sequence to determine the threshold voltages of the memory cells.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.