Automated reference cell trimming verify
US6205056A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 2000 |
| Grant date | Mar 20, 2001 |
| Priority date | — |
| Expiry date | Mar 14, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/3454
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A reference trimming verify circuit and method is provided for performing a program verify operation on a reference cell transistor in an array of Flash EEPROM memory cells. A reference current branch is used to generate a reference current corresponding to a predetermined overdrive voltage of the reference cell to be programmed. A drain current branch is coupled to the reference cell transistor to be programmed and generates a drain current at a fixed gate voltage applied to its control gate and at a predetermined drain voltage applied to its drain when the drain current is at the desired level. A comparator is used to compare a sensed voltage corresponding to the drain current and a reference voltage corresponding to the reference current. The comparator generates an output signal which is at a low logic level when the sensed voltage is less than the reference voltage and which is at a high logic level when the sensed voltage is greater than the reference voltage. A program pulse is applied to the reference transistor each time the comparator generates the low logic level and terminates the program pulse when the comparator generates the high logic level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.