Method and circuit for checking multilevel programming of floating-gate nonvolatile memory cells particularly flash cells
US5880993A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1997 |
| Grant date | Mar 9, 1999 |
| Priority date | — |
| Expiry date | Sep 30, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/5624
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
To check the programming of a nonvolatile memory cell storing an actual threshold value, the drain terminal of the cell is biased at a constant voltage; the gate terminal is biased at a check voltage; the cell is supplied with a predetermined current to determine a gate-source voltage drop related to the actual threshold value; and the voltage at the source terminal is supplied to an input of an operational amplifier. In an open-loop configuration, the desired threshold value of the set predetermined current is supplied as the check voltage; the amplifier compares the source voltage with the ground; and switching of the amplifier indicates the desired threshold value has been reached. In a closed-loop configuration, the output of the operational amplifier is connected directly to the gate terminal of the cell, and supplies the desired threshold value directly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.