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. 25, 2003
Filed:
Oct. 12, 2001
Chi Wa Lo, Tuen Mun, HK;
Howard Cam Luong, Clear Water Bay, HK;
The Hong Kong University of Science and Technology, Hong Kong, CN;
Abstract
A phase locked loop wherein the voltage controlled oscillator is controlled by the output of a phase comparison circuit through a split loop filter. The oscillator has two varactors in parallel in its tuning circuit. The first branch of the loop filter includes an integrator filter generating a first error voltage and the second branch includes a low pass filter generating a second error voltage. The first error voltage controls one varactor and the second error voltage controls the other varactor. As a result the error voltages are effectively summed in the capacitance domain to obviate the need for a dedicated error voltage adder and to allow the total capacitance required in the loop filter to be reduced while still retaining an adequate signal to noise ratio in the filter.