66AK2H14: Long Trace Lengths on High-speed Signals

Joe,

There are several possible devices that can be used to extend the reach of the PCIe, SGMII and SRIO signals.  We will need to get an expert from the that team to respond to this.

Regarding your questions about length: the length limits are benchmarks.  The actual limit is due to many factors such as PCB dielectric material and trace width like you mentioned.  It all comes down to signal loss and PCB traces are very lossy at these frequencies.  The quality of your connectors is also a significant factor.  Fortunately, all three of these interface types are intended to function through connectors and across backplanes.

The interface standards mentioned all have RX signal characteristics, such as eye masks, that must be met for robust operation.  Before you implement a signal re-driver, you might want to create a mock layout of these traces that you can analyse for insertion loss and return loss analysis.  You can then also try different trace widths or PCB materials to determine whether you have a workable solution.  What data rates do you require in your system.  Lower speeds go farther!

Tom

Hi Joe,

The only potential issue with mixing will be length (attenuation) differences between the signals.  This is easily handled using SMBus/EEPROM control which makes each channel configuration independent.  Alternately you could use several smaller devices like the DS80PCI102 and pin configuration to handle signals which have different attenuation characteristics.

Regards,

Lee