Digital method and apparatus for reducing EMI emissions in digitally-clocked systems
US5736893A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 1996 |
| Grant date | Apr 7, 1998 |
| Priority date | — |
| Expiry date | Jan 29, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2215/067
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A clock reference frequency is digitally derived from a base signal, then digitally modulated by ramping the clock reference frequency up and down about a desired frequency. The modulation occurs in periodic fashion at a prescribed modulation frequency. Such modulation spreads the electromagnetic energy of the system signals over a band that is a portion of the desired clock frequency. As a result, energy in harmonics of the respective system signals also are spread. When the energy spreading of any system signal or harmonic of such signal occurs over a bandwidth greater than the 120 kHz bandwidth of conventional communication receivers, adverse EMI emissions are reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.