Guide to cable selection for high speed serial?

[sebmaster]

Hello,

In a project I am looking at using high speed serial links, such as between serialisers/deserialisers like this: **broken link removed**

(If you don't want to read the datasheet, it is for a ChannelLink III serialiser - these chips take ~28 bit data and multiplex them into a single channel along with the clock, transmitted using some form of low voltage differential signal - that chip in the datasheet has an even better ratio than that as it includes 27 bit data + four I2S audio signals.)

At its maximum rate that chip is putting 2.975Gbps down a single pair; what I want to know is, how do I select that pair?

The datasheet specifies a shielded, 100Ω AC coupled twisted pair. I am guessing it also needs a very low characteristic capacitance so not to completely attenuate the signal before its reached even half the operating frequency, but searching for "3Ghz Twisted Pair" doesn't bring up many results.

Is there an application note or some guide which explains how to design the physical connection at these frequencies?

SJ

 

[yura717]

I think you can read about USB 3 specifications

 

[crutschow]

You could use a high speed SATA cable. SATA revision 3.0 cable is good to 6 Gbits/s. These have 100Ω twisted pair signal wires. The cable capacitance is part of the specified 100Ω characteristic impedance (which is determined by the distributed capacitance and inductance of the cable). Both the driver and receiver end of such a cable must be terminated in 100Ω to avoid signal reflection and data errors.