Title :
Sigma-delta modulation techniques for wide spreading range programmable spread spectrum clock generators
Author :
Kholy, Ahmed Ei ; Mokhtar, Ahmed ; Ahmed, Ayman
Author_Institution :
Si-Ware Syst., Cairo, Egypt
Abstract :
Spread Spectrum Clock Generators (SSCG) have recently become a popular method adopted to solve electromagnetic interference (EMI) issues. In this paper, different sigma delta (¿¿) modulators for fractional-N phase-locked loop (PLL) are investigated. Two ¿¿ modulators are implemented, one is a 3rd order single loop modulator and the other is a MASH 1-1-1. A comprehensive comparison between the two modulators designed for SSCG is presented. Spreading is achieved by modulating the feedback divider using a triangular wave through the ¿¿ modulator. In order to allow wide spreading ratios a new technique is adopted to keep the triangular wave within the input range of the ¿¿ modulator.
Keywords :
clocks; electromagnetic interference; feedback; phase locked loops; sigma-delta modulation; signal generators; MASH 1-1-1; electromagnetic interference; feedback divider; fractional-N phase-locked loop; programmable spread spectrum clock generators; sigma-delta modulation techniques; third order single-loop modulator; triangular wave; Clocks; Delta-sigma modulation; Spread spectrum communication; Sigma delta modulation; Spread-Spectrum Clock Generators (SSCG); fractional-N phase-locked loop (PLL);
Conference_Titel :
Design and Test Workshop (IDT), 2009 4th International
Conference_Location :
Riyadh
Print_ISBN :
978-1-4244-5748-9
DOI :
10.1109/IDT.2009.5404097
