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Product category: Frequency Control Components
News Release from: Rakon UK | Subject: CFPT-9400 range
Edited by the Electronicstalk Editorial Team on 10 May 2005

Oscillators cut out reception slips

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A new range of low-jitter high-frequency TCVCXOs is designed for use in TDM switching systems for optical fibre backbone infrastructure.

C-Mac MicroTechnology has launched a range of low-jitter high-frequency TCVCXOs (temperature compensated, voltage controlled crystal oscillators) for use in TDM (time division multiplexing) switching systems for optical fibre backbone infrastructure By using a high-frequency fundamental crystal together with C-MAC's Pluto temperature compensation technology, the new CFPT-9400 range is designed to eliminate reception "slips" that compromise the effective bandwidth of SDH/Sonet and Gigabit Ethernet fibre networks

As telecomms carriers increase datarates across their long-haul fibre infrastructure, it becomes more sensitive to short-term frequency discrepancies between transmitting and receiving equipment, causing faulty reception of data packets.

These discrepancies can be caused by jitter in the signal or by rapid fluctuations in ambient temperature at either end of the fibre.

Improving the jitter performance and temperature stability of the oscillators increases the effective capacity of the fibre network by reducing the number of dropped packets and hence the number of resends required, and so increases the effective capacity of the fibre network.

The CFPT-9400 achieves excellent jitter performance of less than 3ps RMS 10Hz to 80MHz by avoiding the use of a phase locked loop in favour of a low-phase-noise HFF (high-frequency fundamental) crystal and harmonic multiplication.

The HFF crystal is coupled through a SAW (surface acoustic wave) filter, suppressing any subharmonics of the operating frequency to typically less than -55dBc.

The incorporation of Pluto temperature compensation technology keeps frequency stability over the 0 to +80C operating temperature range to +/-1.5ppm.

Besides eliminating temperature-related slips, this allows the CFPT-9400 to keep well within the Telcordia specification of +/-20ppm all-causes stability over a 20-year lifetime.

Because Pluto technology uses an analogue temperature compensation technique, it exhibits superior phase noise characteristics, eliminating another potential source of jitter.

The CFPT-9400 is available in five output frequencies: 622.08000, 666.51436 and 669.32658MHz for SDH/Sonet switches with or without FEC (forward error correction); and 644.53125 and 693.48299MHz for Gigabit Ethernet and emerging 10Gbit Ethernet applications, with or without FEC.

Frequency adjustment of up to +/-60ppm is available through external voltage control.

Supply voltage is 3.3V with a low current consumption of 65mA typical, and output is 3.3V PECL (LVPECL) compatible.

The CFPT-9400 is packaged as an industry standard 14 x 9mm SMD.

It is designed for lead free soldering and compliant with all requirements of the RoHS regulations.

Geoff Trudgen, Senior Design Engineer with C-Mac Frequency Products, commented: "Short-term frequency stability is a hugely important factor in long-haul fibre networks, and will become ever more so as carriers move from today's SDH/Sonet and Gigabit Ethernet technology to 10Gbit/s and beyond".

"Use of Pluto temperature compensation technology in a low-jitter HFF-based oscillator gives us stability to within +/-1.5ppm over temperature range - far better than has previously been possible at such high frequencies - allowing the CFPT-9400 to fulfill the requirements of TDM fibre backbone switches in an efficient and cost effective manner".

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