Read and write operations using constant row line voltage and variable column line load
US6259627A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 27, 2000 |
| Grant date | Jul 10, 2001 |
| Priority date | — |
| Expiry date | Jan 27, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/30
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A read operation for a multi-level or a multi-bit-per-cell non-volatile memory biases a selected row line cell at a fixed voltage that is above the maximum possible threshold voltage representing data and changes the column line load for a selected column line. The column line load that corresponds to the trip-point of a sense amplifier indicates the data stored in the memory cell coupled to the selected row and column lines. A corresponding write process uses the same fixed row line voltage for both program and verify cycles. The programming voltage can be the same as the row line voltage for the read operation or can depend on the data value being written. To better control programming, the duration of the program cycles and/or the load on the drain or source of the selected memory cell during a program cycle varies with time and depends on the value being written. One memory in accordance with the invention includes variable column line loads for use during read and write operations. The variable loads can select the programming current for the write operation or the bias for the read operation according to a data value and/or a count. A counter generating the count for the vari…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.