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