Electronic Design

Unique Synthesized Clock IC Produces Less Than 100-fs Jitter

Jitter is the bane of all designers of buses and communications products where speeds exceed the 1-Gbit/s rate. Multigig’s latest clock ICs can give you more jitter headroom in your design (see the figure). Designated the QuietClock family, this selection of clock products limits rms jitter to typically less than 60 femtoseconds (fs).

As high-speed communications protocols move to 10 Gbits/s, 40 Gbits/s, and higher data rates, timing budgets increasingly get squeezed. Most existing clock and synthesizer solutions cannot achieve the low jitter necessary to minimize dropped packets, enable interoperability between computer systems, and ease performance bottlenecks. Jitter is the key parameter designers want to minimize to unlock higher system throughput.

The QuietClock family provides clock synthesizers that can open constricted eye diagrams, enhance bit error rates (BER), and maximize precious timing margin. These devices also offer three to five times lower jitter and significantly lower phase noise than the typical solution while consuming 30% to 50% less power. Other benefits include higher reliability, frequency programmability, flexibility, and lower cost.

These benefits are derived from Multigig’s patented RotaryWave technology, which makes an oscillator with a travelling wave technique. The heart of the oscillator is a differential transmission line whose length, inductance, and capacitance set the frequency. It is provided with taps and amplifiers to make it a distributed amplifier. The transmission line creates a closed loop with the ends connected together with a one half-twist like in a Mobius strip. The result is a very stable oscillator with low jitter and low phase noise.

QuietClock synthesizers provide an ultralow jitter and phase noise reference clock signal to communication, computing, and networking interface devices. Typical applications include Gigabit Ethernet (1GE), 10 Gigabit Ethernet (10GE), Sonet/SDH, Fibre Channel, Rapid I/O, SATA, and InfiniBand. Most standard frequencies are available.

The product family uses supplies of 3.3 and 2.5 V. These devices incorporate one to 10 outputs from a mix of single-ended (LVCMOS) and differential (LVPECL and LVDS) outputs. They also support the full industrial temperature range (–40°C to 85°C). More than a dozen different models are available. Sampling now, prices start at $2.75 for 1000-unit quantities.

Multigig Inc. www.multigig.com

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