Method and apparatus for synthesizing dual band high-frequency

50 Pages·2013·2.39 MB·English

US 20020008585A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2002/0008585 A1
Welland (43) Pub. Date: Jan. 24, 2002
(54) METHOD AND APPARATUS FOR Publication Classi?cation
SYNTHESIZING DUAL BAND 7
I_IIGI_I_FREQUENCY SIGNALS FOR (51) Int. Cl. . .................. .. H03L 7/099
WIRELESS COMMUNICATIONS (52) US. Cl. .................................. .. 331/2; 331/14; 331/49
(75) Inventor: David R. Welland, Austin, TX (US) (57) ABSTRACT
Correspondence Address: A method and apparatus for synthesizing high-frequency
Brian W- Peterman signals is disclosed that overcomes integration problem
, associated With prior implementations While meeting
lg?aNzga PETERMAN demanding phase noise and other impurity requirements. In
. 3 . one embodiment, a phase-locked loop (PLL) frequency
213stisagg?gggeiisgfhghway South synthesizer is disclosed having a voltage controlled oscilla
’ tor (VCO) With a variable capacitance that includes a
(73) Assigneez Silicon Laboratories’ Inc discretely variable capacitance in conjunction With a con
tinuously variable capacitance. The discretely variable
(21) APPL NO. 09/935,527 capacitance may provide coarse tuning adjustment of the
variable capacitance, and the continuously variable capaci
(22) Filed; Aug 23, 2001 tance may provide a ?ne tuning adjustment of the variable
capacitance. In a further detail, Wireless communication
Related US, Application Data frequency synthesizer for generating multiple band high
frequency signals is disclosed having a ?rst VCO selectable
(63) Continuation of application No. 09/087,649, ?led on for a ?rst frequency band and a second VCO selectable for
May 29, 1998, noW Pat. No. 6,304,146. a second frequency band.
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