Andy! Thanks! I appreciate the info! Deac Work phone: (603) 886-8711 ext.202 Cell : (603) 557-7568 _____ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Andrew Noonan Sent: Thursday, April 28, 2005 12:15 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: NO_RAT property appearing from schematic Hi Deac, It definitely depends on the signaling edge rates coming down the pairs, and to some extent, the data rate. The faster the edge rate, the further away they should be. For example, if the data rate is below 1Gbit/Sec, diff-pairs on inner layers, with geometry of 5/5/5 (line-space-line), you may be able to use a 15 mils air gap between pairs. But as the data rate (and subsequently edge rate) increases, you will need to also increase the space. It gets worse on outer layers, with air as part of the dielectric. So, the short answer is, no rules of thumb, it really depends on the technology you're routing for. Andrew Noonan Sr. PCB Designer Topspin Communications (w)650-316-3398 (c)650-814-3677 -----Original Message----- From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Deac Descoteaux Sent: Thursday, April 28, 2005 8:15 AM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: NO_RAT property appearing from schematic Hi All! Is there a rule of thumb for the distance from a diff pair to the next diff pair? I heard that you should have twice the distance of the overall width or the preceding diff pair. Thanks Deac Work phone: (603) 886-8711 ext.202 Cell : (603) 557-7568 _____ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Gerry Meier Sent: Thursday, April 28, 2005 11:07 AM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: NO_RAT property appearing from schematic Was the property added in Allegro? Gerry Meier Sr. PCB Designer Freedom CAD Services, Inc. Voice: (603) 864-1300 x1350 Alt. Voice: (386) 753-0048 Email: gerry.meier@xxxxxxxxxxxxxx visit our website at<http://www.freedomcad.com <http://www.freedomcad.com/> _____ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Daniel So Sent: Thursday, April 28, 2005 11:04 AM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] NO_RAT property appearing from schematic I am reading in a netlist from Concept which is suppose to have no constraints or properties. However, I am getting a NO_RAT property on the GND net. Doing a search on the ascii files of the schematic pages shows no instances of this property. The property does not appear in any of the dat files created from Concept. Any ideas where this property is coming from? Thanks for any ideas Daniel So 1065 La Avenida Mtn View, Ca 94043 (650) 693-2054 email: danielso@xxxxxxxxxxxxx