Sinusoidal radio-frequency clock distribution system for synchronization of a computer system
AssigneeCompaq Computer Corporation
InventorsDaniel Wissell, Paul A. Galloway
Life of this patent
Estimating the term…
Abstract
A clock generation system generates and distributes sinusoidal signals. Also, the clock lines are configured and shielded in a novel manner so as to provide the same overall propagation characteristics for the clock signals in all the lines, and to minimize the effects of cross-talk and electromagnetic interference.
Claims10
In a digital computer having a plurality of modules having operations which are synchronized by a plurality of digital clock signals, each of said plurality of digital clock signals having a clock frequency, said modules being interconnected for communication therebetween by a synchronous bus and being disposed on a single printed circuit board, an apparatus for generating said plurality of digital clock signals with minimal clock skew, said apparatus comprising:
- a sinusoidal wave oscillator that generates a sinusoidal signal comprising a predetermined fundamental component at said clock frequency which is a fundamental frequency, and another component at harmonics of said clock frequency;
- a low-pass filter coupled with said oscillator for filtering the sinusoidal signal to substantially attenuate said harmonics, thereby producing a filtered sinusoidal signal from said sinusoidal signal;
- signal splitting means coupled to said low-pass filter and connected to a plurality of single-ended clock lines for generating a plurality of copies of said filtered sinusoidal signal without introducing any significant delays in the copies;
- means provided by and on said printed circuit board for distributing said plurality of copies of said filtered sinusoidal signal to said modules, said distribution means comprising a plurality of shielded clock lines of said synchronous bus, and shielding means disposed around said clock lines for shielding said clock lines against externally originating radiation and against emission of radiation from said clock lines at a predetermined range of wavelengths, said clock lines being disposed in said printed circuit board and having approximately the same lengths, material and approximately the same overall signal propagation characteristics;
- and
- converting means coupled to said distributing means and provided on each of said modules for receiving at least one of said plurality of copies of said filtered sinusoidal signal and for converting said received at least one copy of said filtered sinusoidal signal into one of said plurality of digital clock signals, whereby said apparatus provides said plurality of digital clock signals with said minimum clock skew and without requiring skew compensation at said modules, and providing equal overall propagation rates for said plurality of digital clock signals.
In a digital computer having a plurality of modules having operations which are synchronized by a plurality of digital clock signals, said digital clock signals having a clock frequency, said modules being interconnected for communication therebetween by a synchronous bus and being disposed on a single printed circuit board, a method for generating said digital clock signals with minimal clock skew comprising the steps of:
- generating a sinusoidal clock signal including using a sinusoidal-wave oscillator for generating a sinusoidal signal comprising a fundamental component at a pre-selected clock frequency and another component at harmonics thereof;
- filtering the sinusoidal signal to substantially attenuate said harmonics, thereby producing a filtered sinusoidal signal;
- generating a plurality of copies of said filtered sinusoidal signal;
- distributing said plurality of said copies of said filtered sinusoidal signal to said modules along a plurality of single ended clock lines of said synchronous bus disposed in the printed circuit board, said clock lines having approximately the same overall length, material and approximately the same overall signal propagation characteristics;
- shielding said clock lines against externally originating radiation and against the emission of radiation from said clock lines at a predetermined range of wavelengths by a shield provided by said printed circuit board and disposed around said clock lines;
- and
- receiving into each said plurality of modules at least one of said plurality of said copies of said filtered sinusoidal signal and converting said at least one received sinusoidal clock signal into one of said digital clock signals, whereby said method provides said digital clock signals with minimum clock skew and without requiring skew compensation at said modules.
Dependencies are inferred from the claim text.