Method and apparatus to improve immunity to common-mode noise
US5920223A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 1996 |
| Grant date | Jul 6, 1999 |
| Priority date | — |
| Expiry date | Dec 12, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K5/08
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention provides a method and apparatus for improving immunity to common mode noise. The present invention prevents common mode noise from exceeding acceptable limits. The present invention is also useful to prevent common mode noise from being converted to differential mode noise by the action of parasitic diodes. One embodiment of the present invention bleeds charge off two differential lines such that the relative voltage differential is maintained, for example during a memory read, until at least one of the lines is low enough that the maximum possible upward noise (common+differential) is insufficient to turn on the parasitic diodes coupled to the positive voltage supply, leaving enough margin on the differential signal to allow a sensing circuit to accurately sense the differential signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.