Communication line

Consider using USB2.0 magnetics. By using a transformer capable of delivering the differential signal while isolating the grounds, you get your signal across. You can use LVDS without grounding troubles. It may be beneficial to encode the data stream with an 8b/10b scheme to keep DC from pushing the transformer toward saturation. Other, simpler baluns than the USB2.0 magnetics could also get you what you want - I'm just thinking of availability.

There are 100MBit magnetic couplers from Analog Devices. These plus LVDS should do.

Rene

John_H wrote:

The baluns must be transmission-line transformers to work at the frequency desired.

I may be wrong, but my impression is that you can have a balun that is not a transmission line transformer, and it is certainly possible to have a transmission-line transformer that isn't a balun.

I've used exactly this approach, using twisted pair made with 0.15mm diameter enamelled (transformer) wire in a single layer on an RM6 pot core, to carry 8b/10b (TaxiChip) data. It worked fine, but we didn't need to cover 50 metres.

The transformer winding was about one metre long, which meant that the transmission started rolling off above 130MHz.The number of turns (13) and the core inductance gave a low frequency roll-off starting at about

------------ Bill Sloman, Nijmegen

Do you know a partnumber? Because I cannot find any magnetic coupler on Analog's site...

Martin

Thanks, do you know who make these USB2.0 magnetics?

Maybe use a Fast Ethernet phy, together with all the usual Ethernet magnetics and so-on?

Or look into a serializer?

--Mac

Since when are magnetics used in USB2.0?

Meindert