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connectivityZONE Products for the week of August 11, 2008
Vitesse Semiconductor Says…
6.375 Gbit/s SerDes Solution with VScope Waveform Viewing Technology
Solution Integrates SerDes, Signal Integrity & VScope Functionality
Complementary to FPGA and ASIC Solutions
Vitesse Semiconductor Corporation has announced the VSC3441, a 6.375 Gbit/s multi-rate Serialization/De-serialization (SerDes) transceiver device. As the most advanced, high-speed SerDes solution available today, Vitesse’s VSC3441 device operates at selected data rates from 125 Mbps to 6.375 Gbits/s and incorporates advanced equalization to compensate for various impairments and losses encountered in copper cables and backplane traces and connectors. Further adding to the robust feature set of this transceiver is the unique combination of integrated technologies: SerDes, Clock and Data Recovery (CDR) and advanced signal equalization. The VSC3441 is also the first high-speed SerDes to incorporate Vitesse’s breakthrough VScope waveform viewing technology which enables a real-time oscilloscope view of the received data, thus providing telemetry of high-speed signals.
The proliferation of higher speed communication networks creates the need for higher speed serial links to accommodate more bandwidth in backplanes, interconnects and cable links found throughout networking and telecommunications equipment. The VSC3441 provides OEMs a significant new tool that allows them to serialize data to higher rates for simplified transmission through legacy backplanes or cable interconnects. This is achieved by compensating for the signal path degradation which, in turn, improves the signal integrity performance of the transmission. The integrated VScope waveform viewing technology is then used by OEMs for real-time system diagnostics and remote monitoring functions in these applications. The result: a state-of-the-art signal integrity solution that extends the use of existing ASICs and FPGAs with slower speed interfaces.
“With over of decade of leadership in high-speed signal integrity, SerDes and CDR technologies, Vitesse is uniquely qualified to deliver this product,” said Juan Garza, product marketing manager for Signal Integrity solutions at Vitesse. “By incorporating Vitesse’s patented VScope waveform viewing technology into high-speed links, this solution creates a new category for innovative SerDes technology that enables advanced levels of signal integrity quality and remote monitoring.”
With a single reference clock input, the VSC3441 functions at data rates between 125 Mbps and 6.375 Gbits/s. The multi-rate support is well suited for next-generation backplanes and communication equipment running a variety of protocols, including Gigabit Ethernet, XAUI, 2xXAUI, Fibre Channel, Serial Attached SCSI (SAS), Serial ATA (SATA), Serial Rapid IO, Infiniband and PCI Express (PCIe). A high degree of signal integrity is achieved by means of configurable input and output equalization. In various modes, the VSC3441 can function as a single 20:1 SerDes with redundant I/O, a dual 10:1 SerDes with redundant I/O, and a quad 10:1 serializer or quad 1:10 deserializer. The high-speed CDR per channel removes random jitter from optical fiber links. I/O characteristics are programmable for interfacing to a wide variety of devices and protocols.
EN-Genius Says…
The handy VSC3441 6.375 Gbit/s multi-rate transceiver uses much of the SerDes and scope-on-chip capabilities originally introduced in the VC3406 backplane transceiver (reviewed February 2008), but doubles channel capacity and adds a high-speed parallel interface and a configurable interleave/de-interleave switch. This makes it easy for designers designing backplane-based equipment who are still working with legacy ASICs, or lower-cost FPGAs, which don’t have SerDes interfaces. Even if you do work with SerDes-equipped FPGAs, there are enough reports of some devices which have problems running properly at 5 Gbit/s and above that I suspect the VSC3441 may be a better choice in applications where channel conditions are less than ideal.
The VSC3144 performs 8/10/16/20 to 1 Serialization/De-serialization from a set of input pins that can be configured as either a set of plain parallel inputs or as an XGMII connection. The programmable Interleave/de-interleave switch allows it to run as a single 20:1 SerDes with redundant I/O, a dual 10:1 SerDes with redundant I/O, a quad 10:1 serializer, or quad 1:10 deserializer. The device also supports encoded or unencoded parallel interfaces with 8-bit and 16-bit word widths, allowing it to support nearly any SerDes protocol.
 Like the VSC3406 that preceded it, the VSC3441 features a receive equalization scheme that combines a configurable analog feed-forward equalizer (FFE) with a digital decision-feedback equalization (DFE) to provide the extra signal processing needed to pull a clean signal out of a less-than-ideal channel at 6.375 Gbit/s. Each high speed output has a single pole 24-setting analog equalizer coupled to a traditional 8-level digital pre-emphasis circuit.
Almost anybody who’s wrestled with the signal integrity issues that routinely crop up in multi-Gigabit serial links can come up with a dozen reasons why the Vitesse VScope technology is almost a must-have diagnostic tool for developing equipment and for debugging it in the field. Since the VSC3441 on-chip digital signal analysis circuits give you an accurate digitized representation of the actual receive eye, you don’t have to spend $50 k - $100 k on test equipment for basic debugging and analysis. All it takes is a standard PC running Vitesse software to get important information about a particular channel’s attenuation characteristics and quickly develop the proper transmit and receive settings to deal with it. The same capabilities make excellent performance monitoring and diagnostic tools, both during production and in the field. For more information on the VScope feature see my earlier review of the VSC3406.
Now that 3.125 Gbit/s SerDes technology has pretty much become commonplace in backplanes and motherboards, the VSC3441 will help designers prepare for the jump to the doubled line rates that are emerging in the next generation of PCIe Gen2, Serial RapidIO and other major connectivity standards. Vitesse designed the VSC3441 primarily to serve the needs of data and video networking equipment but it should also find many applications in telecom infrastructure – thanks both to the carriers’ relentless migration to IP-based networks and steadily-growing bandwidth requirements. The transceiver's flexible parallel interface should also help it find applications in lower-speed applications where it can provide a seamless bridge between parallel-oriented ASICs or FPGAs and modern serial-oriented systems.
While the VSC3441 power consumption (under 260 mW per active SerDes channel) is not the lowest I’ve seen for a 6+ Gbit/s SerDes device, the extra signal integrity performance it delivers more than justifies the few extra milliwatts it soaks up and should still be low enough for high-density, high-channel count network and carrier equipment.
General samples of VSC3441 devices will be available in Q4 of 2008. The VSC3441 will be priced at $32 in volume quantities in FCBGA-196.
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