If you look carefully at the Xylinx FPGA documents, you will notice that operation of their FPGA's is NOT guaranteed (warranteed) unless a ground plane is employed under it. In most commercial designs of almost any speed, a ground plane is a necessity. --Bob Vasile Surducan wrote: >On 2/4/06, Marcel Birthelmer wrote: > > >>>Use a large numbers of vias between ground planes with the same name on >>>different layers. >>> >>> >>> >>Isn't that a problem as far as ground loops are concerned? >> >> > >No Marcel, this is a fairly common procedure on RF boards. >Every via it's an inductance. The ideea is to minimise the inductance >value between ground planes and have a massive unique ground. >There are a huge numbers of article about this, I suggest Maxim site, >application note about RF transcievers, supply filtering on high >frequency/high slew rate operational amplifiers. > >best regards, >Vasile > > > -- Note: To protect our network, attachments must be sent to attach@engineer.cotse.net . 1-520-850-1673 USA/Canada http://beam.to/azengineer -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist