Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Patent
1996-01-29
1998-04-07
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
327113, 327117, 327100, 377 48, 36472401, 375200, H03D 104
Patent
active
057368937
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.
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Hardin et al., "Spread Spectrum Clock Generation for the Reduction of Radiated Emissions," IEEE Doc #0-7803-1398; Apr. 1994.
Brown Preston D.
Puckette Robert B. E.
Callahan Timothy P.
Hewlett--Packard Company
Le Dinh T.
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