I need your help! Recently we have seen an increasing number of differential structures where the traces are unintentionally imbalanced (for example: Zoo on one side is say 53 Ohms and Zoo on the other is 47 Ohms). This is especially the case on fine line, (2 or 3 mil) PCBs where matching line width to within a tight tolerance can be difficult. My question is: How much imbalance is acceptable? We have found very little information on this subject other than design documents saying diff pairs should be "well matched". If you know of any product specifications that define the required match of differential pairs, or know someone who may be able to help, I would love to hear from you. On behalf of those who are imbalanced - Bob Lazzara VP, Marketing & Tech Support Circuit Connect, Inc. Tel: +1 706.245.4232 (800) 560-9457 Fax: +1 706.245.4299 (888) 453-0520 Web: www.CircuitConnectInc.com