US 7,804,367 B2 · Frequency synthesizer and frequency calibration method

Abstract

A frequency synthesizer capable of using a voltage controlled oscillator (VCO) with a low value of gain Kvco, having a short automatic frequency calibration time and automatically coping with environments and a frequency calibration method are provided. The frequency synthesizer includes a reference divider, a phase detector, a main divider, a charge pump, a loop filter, a first switch, a second switch, a VCO, and an automatic frequency calibration block. The frequency calibration method includes an initialization step, an N-target algorithm step, an auxiliary search algorithm step, and a post search algorithm step.

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Drawings

Claims18

Dependent claims

A frequency synthesizer comprising:

a reference divider which divides a frequency of a reference signal with a division ratio of 1/(R1), wherein the R1 is an integer;
a phase detector which outputs a pulse corresponding to a phase difference between a fine mode signal and a signal output from the reference divider;
a main divider which outputs a coarse mode signal and the fine mode signal by using the output signal of the reference divider;
a charge pump which generates a pumping voltage corresponding to a width and sign of the pulse output from the phase detector;
a loop filter which removes noises generated during operation of frequency calibration loop and determines a voltage level of the pumping voltage;
a first switch which transfers the pumping voltage applied to the one terminal thereof to a VCO (voltage control oscillator) connected to the other terminal thereof in response to a first switch control signal;
a second switch which transfers a reference voltage applied to the one terminal thereof to the VCO connected to the other terminal in response to a second switch control signal;
the VCO which outputs the output signal corresponding to a frequency control signal and a control voltage applied through the first and second switches;
and
a automatic frequency calibration block which generates the frequency control signal, the first switch control signal the first switch control signal, and the second switch control signal in response to the pumping voltage, the reference signal, and the coarse mode signal.

7 more elements

Dependencies are inferred from the claim text.

Description5,818 words

Summary1,986 words

#This application claims priority to Korean Patent Application No. 10-2006-0102283, filed on Oct. 20, 2006, all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in their entirety are incorporated herein by reference.

#1. Field of the Invention

#The present invention relates to a frequency synthesizer, and more particularly, to a frequency synthesizer capable of using a voltage controlled oscillator (VCO) with a low gain Kvco, improving phase noise characteristics, having a short automatic frequency calibration time, and automatically coping with a change of environments.

Brief description of the drawings5 figures

#The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

#FIG. 1 is a block diagram illustrating a conventional fractional-N frequency synthesizer;

#FIG. 2 is a block diagram illustrating a frequency synthesizer according to an embodiment of the present invention;

Detailed description3,708 words

#Hereinafter, exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings.

#FIG. 2 is a block diagram illustrating a frequency synthesizer 200 according to an embodiment of the present invention.

#Referring to FIG. 2, the frequency synthesizer 200 includes a reference divider 210, a phase detector 220, a charge pump 230, a loop filter 240, two switches S1 and S2, a voltage controlled oscillator (VCO) 250, an automatic frequency calibration block 260, and a main divider 270.

Facts

Application

11/872,779Filed 16 Oct 2007

Priority

KR 10-2006-010228320 Oct 2006

Published

US 2008/0106340 A18 May 2008

Granted

28 Sep 2010

Term ends

12 Dec 2028

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 423 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification4 codes

H03L 7/087
Concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal: using at least two…
H03L 7/193
A time difference being used for locking the loop, the counter counting between fixed numbers or the frequency divider dividing by a fixed number:…
H03L 7/1976
For fractional frequency division: using a phase accumulator for controlling the counter or frequency divider
H03L
Automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or

Timeline

20 Oct 2006Priority claimedKR 10-2006-0102283
16 Oct 2007Application filedUS 11/872,779
16 Oct 2007Assigned to Fci Inc.assignment of assignor's interest
8 May 2008PublishedUS 2008/0106340 A1
28 Sep 2010GrantedUS 7,804,367 B2
3 Sep 2020Assigned to Dialog Semiconductor Korea Inc.assignment of assignor's interest
12 Oct 2026TodayWithin its term
12 Dec 2028Term endsEstimated, includes 423 days of adjustment

Frequency synthesizer and frequency calibration method

Life of this patent

Frequency synthesizer and frequency calibration method

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims18

Description5,818 words

Description5,818 words

Drawings

Classification4 codes

Life of this patent