Greetings to all, I've read numerous publications that have said not to route over split planes or to avoid splits at all costs. Well, we have dense boards that require a horde of reference voltages that would force me to have stack-ups greater than 20 layers. I must split these planes and in my case I have to send signals directly over these splits. My Question is.... If I have a 2.0V plane split with a 1.5V rail should I place two capacitors, one on each side of the split to the nearest ground plane. Or should I place one capacitor across the split connecting both Voltage rails (on the same layer). In both cases, we are assuming that the signals of concern are on the layer adjacent to the split. In my eyes the second case seems more attractive.... Lower capacitor count, half the inductance (ESL of one cap as opposed to two) for the return path, real estate. Nonetheless, are there any issues that I may be overlooking in regard to capacitivly (is that how you spell it?) tying two power planes? Would it matter if the difference between the planes were larger.... Such as 5V and 2V? Are there any drawbacks to this configuration whereby the first scenario provides a better return/design? Secondly, My assumptions is that the largest capacitor with the smallest ESL would be optimal. Say ...... I'll use 0.1u for stitching, Is there any guide two determining the circle of influence for a capacitor based on capacitance (This should guide the number of capacitors needed for this application.... And is probably useful for determining bulk capacitor count in the decoupling realm). I'll probably need a few since I have quite a few nets and different busses crossing this split, but I just wouldn't want to over do it!!! Thanks... I Really appreciate all responses, Simba ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu