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:
Jun. 30, 2009
Filed:
Oct. 26, 2004
Laurence D. Lewicki, Sunnyvale, CA (US);
Amjad T. Obeidat, Santa Clara, CA (US);
Nicolas Nodenot, Mountain View, CA (US);
Laurence D. Lewicki, Sunnyvale, CA (US);
Amjad T. Obeidat, Santa Clara, CA (US);
Nicolas Nodenot, Mountain View, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system and method is disclosed for providing a clock and data recovery circuit with a self test capability. A test control unit is provided that causes the clock and data recovery circuit to continuously alter a phase of an interpolated clock signal. A user selects a preselected bit pattern that causes the digital control circuitry of the clock and data recovery circuit to advance or retard the phase of the interpolated clock signal. The test control unit compares the advanced or retarded phase of the interpolated clock signal with a reference clock signal to determine a frequency difference between the two clock signals. The test control unit uses the frequency difference to determine the test status of the clock and data recovery circuit.