Fast pre-programming circuit for floating gate memory
US5539688A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 18, 1995 |
| Grant date | Jul 23, 1996 |
| Priority date | — |
| Expiry date | May 18, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/24
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A circuit for speeding up the pre-programming of floating gate storage transistors such as FLASH EPROMS, and particularly speeding up the pre-programming of a block or array of floating gate storage transistors includes a controllable voltage source that supplies gate programming potential across the control gate and source of the FLASH EPROM transistor cells to be programmed. A control circuit is provided that controls the voltage source to vary the gate programming potential during a programming interval as a function of time in order to decrease the time required for a given amount of charge movement to program the selected floating gate transistors. The wordline voltages are varied, while the source voltage is held constant. By starting at a lower wordline voltage, and increasing during the programming interval to a high wordline voltage, the programming speed is increased, and the high final turn-on threshold voltage for the programmed floating gate storage transistors is achieved. In addition, in order to speed up pre-programming, a programming potential is applied to four wordlines in parallel during a single programming interval. Further, the load on cells being programmed …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.