Hi,

I want to pass ethernet conductors through a PCB,the input is from RJ-45 and the output is to a circular connector.
Do I need to match impedances on the board? do I need to add capacitors/resistors?

*I don't use the the trasmitted data, meaning I don't use PHY component.

Thank you,
Danna

 

Well, you might do that, but you don't say what else will be on the board.

CAT-5 cable has 4 twisted pairs inside; 2 pairs for data and 2 pairs for voice. The twisting keeps the signals from coupling to other pairs.

If you run the signals across a board without some kind of shielding, they may pick up ambient noise or noise from the board; they won't be twisted any more unless you make the traces "twist".

[eta]
Here's an application note from Micrel: http://www.micrel.com/_PDF/Ethernet/app-notes/an-111.pdf
You should have a look.

 

I also have on the board a lot of components (FPGA,prom,trancievers, clocks,SRAM,flash and etc).
how do I keep the twisting on the board? Do I use 100ohm controlled trace and Keep both traces of each differential pair as identical to each other as possible?

Thank you,
Danna