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

fYear

2009

fDate

15-17 Nov. 2009

Firstpage

1

Lastpage

5

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 (Â¿Â¿) modulators for fractional-N phase-locked loop (PLL) are investigated. Two Â¿Â¿ modulators are implemented, one is a 3^rd 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 Â¿Â¿ modulator. In order to allow wide spreading ratios a new technique is adopted to keep the triangular wave within the input range of the Â¿Â¿ 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);

fLanguage

English

Publisher

ieee

Conference_Titel

Design and Test Workshop (IDT), 2009 4th International

Conference_Location

Riyadh

Print_ISBN

978-1-4244-5748-9

Type

conf

DOI

10.1109/IDT.2009.5404097

Filename

5404097