The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 07, 2006
Filed:
Oct. 06, 2000
Andrew K. Percey, San Jose, CA (US);
John D. Logue, Placerville, CA (US);
F. Erich Goetting, Cupertino, CA (US);
Paul G. Hyland, County Kildare, IE;
Andrew K. Percey, San Jose, CA (US);
John D. Logue, Placerville, CA (US);
F. Erich Goetting, Cupertino, CA (US);
Paul G. Hyland, County Kildare, IE;
Xilinx, Inc., San Jose, CA (US);
Abstract
The frequency of a skew clock signal is dithered around a base frequency, thereby enabling this clock signal to comply with FCC requirements for electromagnetic emissions within a specified window. Delay is introduced such that the clock signals exhibits slightly different frequencies in successive periods. For example, the frequency of a 100 MHz clock signal can be adjusted to have frequencies of approximately 98, 98.5, 99, 99.5, 100, 100.5, 101, 101.5, and 102 MHz during different periods. Because the frequencies are spread in 0.5 MHz increments, only three frequencies are included in any 1 MHz window. As a result, ⅔ of the energy of the clock signal is not included when determining whether the clock signal meets the FCC electromagnetic emission requirements. By spreading the frequencies above and below the base frequency in a regular manner, the average frequency of the clock signal becomes equal to the base frequency.