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US4802124A
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Non-volatile shadow storage cell with reduced tunnel device count for improved reliability
Assignee: STMicroelectronics lnc USA
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Filing: 1987-08-03
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Granted: 1989-01-31
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Expires: 2007-08-03
Abstract
Abstract A non-volatile storage cell utilizing a single isolation device, preferably of the Fowler-Nordheim tunneling type for each non-volatile cell module and wherein an improved level shifting input/output circuit is incorporated into each such cell.
Inventors
- 👤 George D. O'Brien, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:25
CPC Classifications
G; G11; G11C; G11C14/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
80 words
A non-volatile shadow memory cell controlled by input switching signals, the combination comprising: a non-volatile storage element; an isolation element for charging and discharging said non-volatile storage element; means for charging said non-volatile storage element in a first direction, said means for charging said non-volatile storage element comprising said isolation element; and means for discharging said non-volatile storage element in a second direction, said means for discharging said non-volatile storage element comprising said isolation element to provide a discharging current.
Claim 2
Dependent Claim
80 words
A non-volatile shadow memory cell controlled by input switching signals, the combination comprising: a non-volatile storage element; an isolation element for charging and discharging said non-volatile storage element; means for charging said non-volatile storage element in a first direction, said means for charging said non-volatile storage element comprising said isolation element; and means for discharging said non-volatile storage element in a second direction, said means for discharging said non-volatile storage element comprising said isolation element to provide a discharging current.
Claim 3
Dependent Claim
38 words
The non-volatile shadow memory cell in accordance with claim 1 wherein at least one of said means for charging and said means for discharging further comprises: input/output means for level shifting the switching signal to said isolation element.
Claim 4
Dependent Claim
19 words
The non-volatile shadow memory cell in accordance with claim 1 wherein said isolation element comprises: a Fowler-Nordheim tunneling element.
Claim 5
Dependent Claim
38 words
The non-volatile shadow memory cell in accordance with claim 3 wherein at least one of said means for charging and said means for discharging further comprises: input/output means for level shifting the switching signal to said isolation element
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-31 | 1992-08-01 | 1993-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-31 | 1996-08-01 | 1997-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-31 | 2000-08-01 | 2001-01-31 | $7700.00 | Window Closed / Lapsed |