07786772 is referenced by 3 patents and cites 15 patents.

A method and apparatus for reducing in-band spurs in a fractional-N synthesizer (100) includes generating a compensated current signal by a charge pump (108) coupled to a phase detector (106). The compensated current signal includes in-band spurs having frequencies within a frequency bandwidth associated with a loop filter (110). The method then includes selectively dithering the compensated current signal with a sufficient dither level to spread the frequencies of in-band spurs beyond the frequency bandwidth associated with the loop filter (110). The dithered compensated current signal is then passed through the loop filter (110) for filtering the in-band spurs having frequencies beyond the frequency bandwidth. The method then includes generating a voltage controlled oscillator (VCO) signal with reduced in-band spurs proportional to the filtered compensated current signal.

Title
Method and apparatus for reducing spurs in a fractional-N synthesizer
Application Number
12/131035
Publication Number
7786772 (B2)
Application Date
May 30, 2008
Publication Date
August 31, 2010
Inventor
Paul H Gailus
Prospect Heights
IL, US
Joseph A Charaska
Melrose Park
IL, US
John J Bozeki
Elgin
IL, US
Manuel P Gabato Jr
Elmhurst
IL, US
Agent
Barbara R Doutre
Assignee
Motorola
IL, US
IPC
H03L 7/06
View Original Source