Method and apparatus for controlling phase of a system clock signal for switching the system clock signal
US5373254A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jan 15, 1993 |
| Grant date | Dec 13, 1994 |
| Priority date | — |
| Expiry date | Jan 15, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/143
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for controlling the phase of a system clock, in which one of a first clock signal and a second clock signal is selected and output to a system as a system clock signal, the first clock signal being generated by a frequency synthesizer synchronized with an external clock signal supplied from a reference clock signal oscillator provided externally of the system, and the second clock signal being supplied from another reference clock signal oscillator provided internally of the system, and the phases of the first and second clock signals are controlled, prior to switching between the first and second clock signals and supplying the switched clock signal to the system as the system clock signal. The switching is delayed for a period while there is a phase shift between the first and second clock signal , when the system clock signal is switched between the first and second clock signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.