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:
Sep. 16, 2003
Filed:
Nov. 22, 2000
Kouzou Ichimaru, Kunisaki-machi, JP;
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
The present invention pertains to a type of frequency synthesizer which can correctly compensate for the ripple current. Frequency synthesizer has PLL loop containing oscillator and charge pump circuit . Also, the frequency synthesizer has compensating circuit and correcting circuit . Said correcting circuit has sense amplifier , up/down counter , and DA converter . The compensating circuit superimposes a compensating current onto the output current of charge pump circuit which generates the control signal of oscillator , and it compensates for the ripple current contained in the output current. After the PLL loop is locked, sense amplifier detects the ripple current with the superimposed compensating current, and based on the detection result, up/down counter and DA converter control compensating circuit , and the difference between the ripple current and the compensating current is reduced. Consequently, even when the ripple current varies due to variation in the circuit constants, etc., it is possible to cancel out the ripple current accurately.