Abstract

Networking equipment must support a diverse and growing set of data rates including 10 G Ethernet. 10 G Fibre Channel. SONET OC-192 and the associated forward error correction (FEC) rates. Traditional timing sub-system architectures use a single crystal or SAW resonator for each frequency resulting in a plethora of individual oscillators on each port card. By using a DSP-based clock synthesis IC. multiple output frequencies can be generated from a single. low-frequency crystal resonator. Integrating the clock synthesis IC with the low-frequency quartz crystal into a hermetic ceramic package enables the development of multiple frequency crystal oscillator (XO) and voltage-controlled crystal oscillator (VCXO) devices. Key specifications. such as frequency stability. long-term aging. drift and mechanical integrity. are significantly improved over high-frequency fundamental (HFF) crystals or SAW-based oscillators.

© 2006 Optical Society of America