Wide Frequency-Range Spread-Spectrum Clock Generator with Digital Modulation Control

Takashi KAWAMOTO  Masato SUZUKI  Takayuki NOTO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E96-C   No.6   pp.935-941
Publication Date: 2013/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E96.C.935
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Circuits
Keyword: 
spread-spectrum clock generator,  PLL,  VCO,  multi-modulus divider,  

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Summary: 
A technique that enables a SSCG to fine-tune an output signal frequency and a spread ratio is presented. Proposed SSCG achieves the output signal frequency from 1.2 GHz to 3.0 GHz and the spread ratio from 0 to 30000 ppm. The fine-tuning technique achieves 30 ppm adjustment of the output signal frequency and 200 ppm adjustment of the spread ratio. This technique is achieved by controlling a triangular modulation signal characteristics generated by a proposed digital controlled wave generator. A proposed multi-modulus divider can have a divide ratio of 4/5 and 8/9. This SSCG has been fabricated in a 0.13-µm CMOS process. The output signal frequency-range and the spread ratio are achieved fluently from 0.1 to 3.0 GHz and from 0 to 30000 ppm, respectively. EMI noise is suppressed at less than 17.1 dB at the output signal frequency of 3.0 GHz and spread ratio of 30000 ppm.