For multilayer pcb layout it is sometimes recommended to make windows in ground and power planes near pins/pads of high speed OpAmps, see datasheet of OPA656 page 14:
a) Minimize parasitic capacitance to any AC ground for all of the signal I/O pins. Parasitic capacitance on the output and inverting input pins can cause instability—on the noninvert- ing input, it can react with the source impedance to cause unintentional bandlimiting. To reduce unwanted capacitance, a window around the signal I/O pins should be opened in all of the ground and power planes around those pins. Other- wise, ground and power planes should be unbroken else- where on the board. Is there a way to to make such windows for pcb, or have I to build the planes from tiny rectangles? (I have a 6-layer pcb, all OpAmps are SMD, second layer is groud plane.) Nest regards Stefan Salewski _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
