Samtec brings Optics to PCIe
July 2012 – With the rise of PCIe interface peripherals, especially in the industrial marketplace, Samtec introduced a new optical fiber solution for extended distances to suppliment the current copper based extension technology. The products have been submitted and has been approved by the PCI SIG as part of their standard.
The cabling supports a 5GT/s when used for up to 300M, and 8GT/s up to 100M. The cabling is much lighter in weight and power draw per transaction over a copper solution, while fitting into the same sockets and connectors. The optical solution (called an Active Optical Cable or AOC) implements the design on a paddle board connector with the cable. The design from Samtec is for PICe 2.x and features :
- Link Training
- Electrical Idle
- Auxiliary signals / sidebands: cable present, wake, reset, power on
- Power up/down from either side
- 100 MHz clock forwarding (asynchronous)
This configuration allows PCIe Gen3 speeds with the Gen2 interface and up to 8 lanes of connection. It can be configured as a 2×4 lane configuration and also a 1×8 lane configuration. The AOC solution is different from standard networking optical cables such as QSFP, as the PCIe electrical Idle is not compatible with edge networking protocols which will cause the standard cables to not link. As a result the electronics need to add an optics mode and idle signal cue to the base electronics spec. Another constraint is the clock management in the cabling solution. As result, the optical solution requires a clock isolation card for supporting links over 7m to mange spread spectrum clocking of the PCIe Gen 2 specification.
Samtec Optical Fiber for PCIe technology
In addition to dual connector solutions, the cables are also available as a single ended active solution with a passive connector on the other end for front panel connection applications. All of these solutions operate at 3.3v and are available now.
