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US5491458A
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Apparatus for spreading the spectrum of a signal and method therefor
Assignee: Lexmark International Inc
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Filing: 1994-11-08
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Granted: 1996-02-13
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Expires: 2014-11-08
Abstract
Abstract An oscillator generates a signal that is applied to one input of a phase shifter circuit. The other input of the phase shifter is connected to a source of a phase modulation signal. In response to the phase modulationsignal, the phase shifter provides a clock signal with a spread spectrum.
Inventors
- 👤 Earl W. McCune, Jr.
- 👤 Narendar Venugopal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:29
CPC Classifications
H; H04; H04B; H04B15/00; H04B15/02; H04B15/04; H03; H03B; H03B1/00; H03B1/04; H03B2202/00; H03B2202/08; H03C; H03C3/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
72 words
Apparatus for causing a clock signal of a digital system to have a power density spectrum, comprising: an oscillator; a source of a periodic phase modulation signal; means for phase modulating the output of said oscillator in response to said phase modulation signal, said phase modulation signal causing said means to provide a phase modulated signal with a power density spectrum within a known bandwidth, said power density spectrum being substantially flat.
Claim 2
Dependent Claim
72 words
Apparatus for causing a clock signal of a digital system to have a power density spectrum, comprising: an oscillator; a source of a periodic phase modulation signal; means for phase modulating the output of said oscillator in response to said phase modulation signal, said phase modulation signal causing said means to provide a phase modulated signal with a power density spectrum within a known bandwidth, said power density spectrum being substantially flat.
Claim 3
Dependent Claim
13 words
Apparatus according to claim 1 wherein said means includes a phase shifter circuit.
Claim 4
Dependent Claim
104 words
Apparatus in accordance with claim 1 wherein a single period of said phase modulation signal is in accordance with a relationship which is given as: ##EQU2## where: S(t) is a single period of the phase modulation wave form; C is an offset constant of the form (1-p)BP/16+pBP/8; K 1 is a first gain constant of the form 2pB/P; K 2 is a second gain constant of the form (1-p)B/4(p/4) 3 ; P is the period of the modulation wave form; B is said bandwidth of said power density spectrum resulting from the phase modulation; and p is a scaling factor between 0 and 1.
Claim 5
Dependent Claim
64 words
In the method of spreading the power density spectrum of a clock signal of a digital system, the steps of: generating an oscillator signal; and phase modulating said oscillator signal in response to a phase modulation signal, a result of said modulation being a modulated oscillator signal that has a power density spectrum within a known bandwidth, said power density spectrum being substantially flat.
Claim 6
Dependent Claim
64 words
In the method of spreading the power density spectrum of a clock signal of a digital system, the steps of: generating an oscillator signal; and phase modulating said oscillator signal in response to a phase modulation signal, a result of said modulation being a modulated oscillator signal that has a power density spectrum within a known bandwidth, said power density spectrum being substantially flat.
Claim 7
Dependent Claim
104 words
In the method of claim 4 wherein a single period of said phase modulation signal is in accordance with a relationship which is given as: ##EQU3## where: S(t) is a single period of the phase modulation wave form; C is an offset constant of the form (1-p)BP/16+pBP/8; K 1 is a first gain constant of the form 2pB/P; K 2 is a second gain constant of the form (1-p)B/4(P/4) 3 ; P is the period of the modulation wave form; B is said bandwidth of a power density spectrum resulting from the phase modulation; and p is a scaling factor between 0 and 1.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-02-12 | 1999-08-14 | 2000-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-02-12 | 2003-08-14 | 2004-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-02-12 | 2007-08-14 | 2008-02-13 | $7700.00 | Window Closed / Lapsed |