1
Keith B Hardin, John T Fessler, Donald R Bush, James J Booth: Spread spectrum clock generator and associated method. Lexmark International, Bell Seltzer Park & Gibson, January 30, 1996: US05488627 (116 worldwide citation)

A clock circuit includes an oscillator for generating a reference frequency signal, and a spread spectrum clock generator cooperating with the oscillator for generating a spread spectrum clock output signal having a fundamental frequency and reduced amplitude EMI spectral components at harmonics of ...


2
John B Berry, James R Booth, Keith B Hardin, John P Richey: Method and apparatus for providing a clock generation circuit for digitally controlled frequency or spread spectrum clocking. Lexmark International, John A Brady, April 2, 2002: US06366174 (104 worldwide citation)

An improved clock generation circuit is provided that operates with a single input clock frequency, and includes a Phase Locked Loop circuit (PLL) with a digital accumulator in the feedback loop, in which either the Most Significant Bit or the Carry Bit of the binary adder is used as the modulated f ...


3
Keith B Hardin: Spread spectrum clock generator. Lexmark International, John A Brady, May 20, 1997: US05631920 (87 worldwide citation)

A clock circuit includes an oscillator for generating a reference frequency signal, and a spread spectrum clock generator cooperating with the oscillator, generating a spread spectrum clock output signal having a fundamental frequency and reduced amplitude EMI spectral components at harmonics of the ...


4
Keith B Hardin, Robert A Oglesbee, John P Richey: Method and apparatus for reducing EMI emissions for data signals traveling over a data pathway. Lexmark International, Frederick H Gribbell, April 7, 2009: US07515646 (1 worldwide citation)

An improved data signal electromagnetic emissions system is provided for sending data signals over one or more data pathways. An original data signal is encoded into a set of sideband frequencies that exhibit a lower amplitude than the original data signal; then transmitted over the data pathway and ...


5
John B Berry, Keith B Hardin, John P Richey: Low electromagnetic emissions and improved signal quality video drive architecture for laser printers. Lexmark International, wang maohua, January 2, 2002: CN99814195

An electrophotographic image forming apparatus transfers image information relating to an image to be formed on a medium, while maintaining desired low levels of electromagnetic emissions. The apparatus includes an image processor that generates low-frequency image information signals containing the ...


6
Keith B Hardin, Robert A Oglesbee, John P Richey: Method and apparatus for reducing EMI emissions for data signals traveling over a data pathway. Lexmark International, Intellectual Property Law Department, August 25, 2005: US20050185731-A1

An improved data signal electromagnetic emissions system is provided for sending data signals over one or more data pathways. An original data signal is encoded into a set of sideband frequencies that exhibit a lower amplitude than the original data signal; then transmitted over the data pathway and ...


7
Keith B Hardin, Robert A Oglesbee: Segmental spectrum clock generator apparatus and mehtod for using same. Lexmark International, li qiang, January 28, 2004: CN01817801

A segmented spectrum clock generator (100) provides a signal (300) with a frequency response having multiple segments with a sharp rolloff of at least 10 dB on both sides of each individual segment's peak amplitude across the entire spectrum. A frequency synthesizer (preferably a phase locked loop) ...