Read circuits for analog memory cells
US5751635A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1996 |
| Grant date | May 12, 1998 |
| Priority date | — |
| Expiry date | Jan 11, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/5621
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Circuits and processes write and read analog signals in non-volatile memory cells such as EPROM and flash EPROM cells. One read circuit process determines a memory cell's threshold voltage by slowly ramps the control gate voltage of a memory cell being read and senses when the memory cell conducts. Another read circuit determines the threshold voltage of a memory cell using a source follower read process and a ramping circuit which slowly increases the source voltage. Still another read circuit includes a cascoding device connectable to a memory cell, bias circuit for biasing the memory cell in its linear region, and a load which carries a current that mirrors the current through the memory cell wherein the threshold voltage of the memory cell is determined from a voltage across the load. Read circuits disclosed can be used with analog memory cells, binary memory cells, multi-level digital memory cells, and other applications which require precise reading of threshold voltages.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.