Method and apparatus for frequency modulating a periodic signal of varying duty cycle
US7561002B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 2005 |
| Grant date | Jul 14, 2009 |
| Priority date | — |
| Expiry date | Oct 5, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2215/067
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for frequency modulating a PWM involves 1) generating a high frequency carrier signal much greater in frequency than the PWM signal; 2) modulating the high frequency signal to generate a spread spectrum carrier signal; and, 3) retiming a PWM signal with this high frequency SS carrier signal so that the binary transitions of the PWM signal are aligned with the frequency varying carrier signal. In another embodiment, a PWM oscillator is driven by a second, FM oscillator having spread spectrum characteristics. In another embodiment a PWM oscillator is driven and modulated by a counter/frequency divider comprised of modules.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.