PCIe Gen2 boosts lane rates to 500 Mbytes/sec
By Maury Wright, Editorial Director -- EDN, September 18, 2007
The second generation of PCIe (Peripheral Component Interconnect Express) technology is upon us with vendors planning new IC families and support chips. Meanwhile, PCIe 1.1 technology moves to enable embedded-system applications with more highly integrated, low-power chips set to debut. The PCIe Gen2 (Generation 2) standard doubles the data rate possible in each lane of the scalable serial interface to 500 Mbytes/sec. As with the first generation of PCIe technology, designers can combine as many as 32 lanes to support escalating bandwidth demands.
PCIe found immediate adoption in connecting graphics cards inside PCs and has found usage in servers and communications gear. The Gen2 technology will target similar applications. In applications other than within a PC, a PCIe switch serves as the heart of the system architecture. PLX Technology has offered a broad line of PCIe switches in its PEX8000 family and is now adding six Gen2 switches to the family. The new family includes switches with 12 to 48 lanes and three to 12 ports.
The ICs support load balancing and a dual-cast feature, which allows the switch to forward data to multiple output ports. PLX claims that flip-chip packaging maximizes signal integrity. Moreover, the switches can dynamically set lane rates and power down unused functional blocks to minimize power consumption. Typical system configurations range from the 32-lane, eight-port PEX 8632 in a workstation-graphics role to the 48-lane, 12-port PEX 8648 in a server-backplane-fabric role. Prices range from $25 to $75 (volume quantities), samples will become available in the fourth quarter of this year, and production units will become available in the first quarter of 2008.
IDT, which in the spring announced 12-lane, three-port and 16-lane, four-port Gen2 switches has targeted low cost and low power with its latest announcement. The new PCIe 1.1 switches range from the three-lane, three-port 89PES3T3 to the eight-lane, five-port 89PES8T5A, and prices from $7.60 to $12.80 (volume quantities). IDT claims that the new ICs are the industry’s smallest PCIe switches and offers them in no-lead QFN packages. Target applications include automotive, medical, and consumer applications with relatively low lane- and port-count requirements.
You can also expect support chips such as driver ICs for Gen2 to hit the market by the first quarter of next year. Pericom, for example, plans to ship a Gen2 version of its PCIe ReDriver IC in that time frame.
