Non-volatile memory program driver and read reference circuits
US6219279A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1999 |
| Grant date | Apr 17, 2001 |
| Priority date | — |
| Expiry date | Oct 29, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/26
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and circuits, in a non-volatile memory system such as EPROM, for limiting bit line current during programming that includes biasing a driving transistor to mirror a maximum desired current into the driving transistor from a mirroring transistor connected to a controlled current source. This technique is useful, for example, during hot electron programming of a floating gate memory cell to limit bit line current caused by snap back of the cell through which a relatively high current is passed. In a preferred embodiment, the state of a cell is monitored while being programmed by comparing the voltage of the bit line with a reference voltage that is developed in a circuit containing a replica of the driving transistor. Since characteristics of the driving and reference transistors are the same from wafer to wafer, or batch to batch, the reference voltage varies to compensate for variations in characteristics of the driving transistor among integrated circuit chips from different wafers and manufacturing batches.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.