A Spread Spectrum Clock Generator Using Digital Tracking Scheme

Takefumi YOSHIKAWA  Tsuyoshi EBUCHI  Yukio ARIMA  Toru IWATA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C   No.6   pp.1288-1289
Publication Date: 2005/06/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.6.1288
Print ISSN: 0916-8516
Type of Manuscript: Special Section LETTER (Special Section on Analog Circuit and Device Technologies)
Category: PLL
Keyword: 
PLL,  spread spectrum clocking,  EMI,  phase interpolator,  

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Summary: 
A Spread Spectrum Clock Generator (SSCG) using Digital Tracking scheme (DT-SSCG) is described. Using digital tracking control outside a PLL, DT-SSCG can realize stable modulation characteristic independent of the PLL constants. Moreover, DT-SSCG can apply to various modulation profiles easily by brief change of the digital tracking parameters. A test chip has realized the fitting of 5000 ppm downspread with 6.02 dB and 8.02 dB spectrum peak reduction for triangle and Non-Linear modulation.