I would like to incorporate balanced differential traces (120 Ohms), 
     preferably in a microstrip configuration, on a PWB. I am having great 
     difficulty in tracking down equations for this configuration (IPC-2141 
     indicates that the equations are "in process").
     Can anyone help with this?
     Can I use two parallel traces, each of 60 Ohms with reference to a 
     ground plane, to achieve the same effect. I seem to remember that, in 
     order to do this, the traces would have to be quite a distance apart 
     to minimize the effect that proximity would have on the overall 
     impedance, and also, that by moving them apart, the "balanced" effect 
     is greatly diminished in terms of field cancellations, etc..
     
     Any info on this subject is greatly appreciated.
     
     Max.P.Harris
     Hardware Design Engineer
     Lockheed Martin Canada, Inc.

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