Sigma-delta modulation techniques for wide spreading range programmable spread spectrum clock generators
- Resource Type
- Conference
- Authors
- Kholy, Ahmed El; Mokhtar, Ahmed; Ahmed, Ayman
- Source
- 2009 4th International Design and Test Workshop (IDT) Design and Test Workshop (IDT), 2009 4th International. :1-5 Nov, 2009
- Subject
- Communication, Networking and Broadcast Technologies
Computing and Processing
Components, Circuits, Devices and Systems
Delta-sigma modulation
Spread spectrum communication
Clocks
Sigma delta modulation
fractional-N phase-locked loop (PLL)
Spread-Spectrum Clock Generators (SSCG)
- Language
- ISSN
- 2162-0601
2162-061X
Spread Spectrum Clock Generators (SSCG) have recently become a popular method adopted to solve electromagnetic interference (EMI) issues. In this paper, different sigma delta (ΣΔ) modulators for fractional-N phase-locked loop (PLL) are investigated. Two ΣΔ 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 ΣΔ modulator. In order to allow wide spreading ratios a new technique is adopted to keep the triangular wave within the input range of the ΣΔ modulator.