Spread spectrum clock generator

A clock circuit includes a clock pulse generator (22-32) for generating a series of clock pulses, and a spread spectrum modulator (36-42) for frequency modulating the clock pulse signal from the clock pulse generator (22-32) to broaden and flatten amplitudes of EMI spectral components at harmonics o...

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Bibliographische Detailangaben
1. Verfasser:	HARDIN, KEITH B
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATIONOF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES BASIC ELECTRONIC CIRCUITRY CALCULATING COMPUTING COUNTING ELECTRIC COMMUNICATION TECHNIQUE ELECTRIC DIGITAL DATA PROCESSING ELECTRICITY GENERATION OF NOISE BY SUCH CIRCUITS GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING,BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN ANON-SWITCHING MANNER MODULATION MULTIPLEX COMMUNICATION PHYSICS PULSE TECHNIQUE TRANSMISSION
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Beschreibung
Zusammenfassung:	A clock circuit includes a clock pulse generator (22-32) for generating a series of clock pulses, and a spread spectrum modulator (36-42) for frequency modulating the clock pulse signal from the clock pulse generator (22-32) to broaden and flatten amplitudes of EMI spectral components at harmonics of the fundamental frequency of the clock pulse signal which would otherwise be produced by the clock pulse generator. The spread spectrum modulator (36-42) frequency modulates the clock pulses with specific profiles of frequency deviation versus the period of the profile. The clock generator circuits are digital and may be reset to a starting condition to synchronize the spread spectrum clock, e.g. counter 40 may be reset. For a laser printhead, the clock circuit is synchronized with a start-of-sweep signal, so that printing is not degraded.