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Altera_Forum
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15 years ago

Matching Cyclone III Signal Impedance to 65Ohm cPCI Traces

I am using an EP3C55F780I7 device to act as an interface between my peripheral board and a cPCI backplane. By specification, cPCI signal traces must be 65 Ohms +/- 10%. In reading through the various...
Altera_Forum's avatar
Altera_Forum
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15 years ago

If your cPCI interface device is close to the cPCI connector, you don't need to have 65-Ohms on your PCB. Its more important that you have 10-ohm stub terminations, or if you want hot-swap cPCI use bus switches near the cPCI connector.

For example, here's a board that uses a PowerPC for a hot-swappable cPCI interface and Stratix II FPGAs:

http://www.ovro.caltech.edu/~dwh/carma_board/ (http://www.ovro.caltech.edu/%7edwh/carma_board/)

http://www.ovro.caltech.edu/~dwh/carma_board/gda06rb004_carma_v0.87_dec03.pdf (http://www.ovro.caltech.edu/%7edwh/carma_board/gda06rb004_carma_v0.87_dec03.pdf)

and here's one that uses a PLX9054 for a regular cPCI interface:

http://www.ovro.caltech.edu/~dwh/correlator/pdf/correlator_sch_rev_c1.pdf (http://www.ovro.caltech.edu/%7edwh/correlator/pdf/correlator_sch_rev_c1.pdf)

Cheers,

Dave