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:
Aug. 06, 1996
Filed:
Oct. 11, 1994
Keith K Onodera, Berkeley, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system including a reference oscillator, a controlled oscillator, a digital phase detector, and a digital loop filter uses a method for matching a first oscillation frequency of the controlled oscillator with a second oscillation frequency of the reference oscillator by variably selecting different capacitances and/or resistances of the controlled oscillator using switches. The first and second oscillation frequencies are provided to the digital phase detector, where they are compared to determine an output signal which is indicative of the difference between the first and second frequencies. The output signal is transmitted to a digital loop filter, which converts the output signal into control words. The control words are sent to the controlled oscillator so that the first oscillation frequency can be varied as needed. The controlled oscillator may be a capacitor controlled oscillator (CCO), a resistor controlled oscillator (RCO), or a resistor-capacitor controlled oscillator (RCCO).