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:
Jan. 05, 2010
Filed:
Sep. 06, 2005
Daniel R. Meacham, La Jolla, CA (US);
Daniel R. Meacham, La Jolla, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
Using low impedance switches and coupling to a virtual ground, one or more capacitors are selectively switched into or out of an inductive-capacitive resonant circuit portion of an integrated circuit filter to alter the resonant frequency based on a phase difference between the resonant frequency and a reference frequency. The capacitors are sized for a sequence of total capacitances proceeding by halves or doubles between values corresponding to minimum and maximum desired frequency adjustments, allowing a binary count of pulses representative of the phase difference to address the correct combination of capacitors. An exact or ratioed replica of the inductive-capacitive resonant circuit, controlled by the same capacitance selection signal, may be used as a frequency-selective amplifier load or matching network, or to form a ladder filter.