Variable delay compensation for data-dependent mismatch in characteristic of opposing devices of a sense amplifier
US6762961B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 2002 |
| Grant date | Jul 13, 2004 |
| Priority date | — |
| Expiry date | Sep 19, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C7/065
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Post-manufacture variation of timing may be employed to address data-dependent degradation or creep in device characteristics affecting a differential circuit. One particular example of such data-dependent degradation or creep involves Negative Bias Temperature Instability (NBTI). In certain memory circuit configurations, NBTI can cause threshold voltage (Vt) of PMOS devices to increase by an amount that depends on the historical amount of voltage bias that has been applied across gate and source/drain nodes. In the case of many sense amplifier designs, a predominant value read out using the sense amp may tend to disparately affect one device (or set of devices) as compared with an opposing device (or set of devices). In other words, if the same data value is read over and over again, then one of two opposing PMOS devices of a typical sense amp will accumulate an NBTI-related Vt shift, while the opposing PMOS device will accumulate little or no shift. The accumulated mismatch tends to cause an increase in the sense amp fail-point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.