How much does the impendence matter?

[presto]

Hi, there,

I'm going to design an adaptor board connecting a SFP fibre transceiver (2.5Gb) to a SMA or SATA type connector. Since the trace of 2.5Gb signal will be under 1 inch, I wonder if the impendence of the 4-layer PCB still needs to be carefully matched or general fabrication should be fine?

Many thanks

 

[flatulent]

This is a significant fraction of a wavelength so you should consider it. Your biggest problems will be the transitions to the connectors on the ends. The manufacturers of the parts probably have application notes on how to shape the traces at the transitions.

 

[spikeyang]

Just use 50 Ohm microstrip line to the SMA connectort. It will not be much insertion loss.
Make sure what the width of your copper microstrip line. Avoid via hole s, iwhi
which will make impedance change.