Subject:                              Time:  9:33 AM
  OFFICE MEMO         DES: True Differential Striplines     Date:  6/6/96

Hi all, we have a problem finding the design requirements (formulas) for true
differential strip transmission lines, see the following sketch

sgsgsgsgsgsgsgsgsgsgs -- the sg's are signal grounds (planes)
ddddddddddddddddddddd -- the d's are dielectric
ddddddddddddddddddddd
ddddddddsssssssdddddd -- the s's are signal layers (superimposed)
ddddddddddddddddddddd
ddddddddsssssssdddddd
ddddddddddddddddddddd
ddddddddddddddddddddd
sgsgsgsgsgsgsgsgsgsgs

We have done a bunch of literature searches to find the formulas to model
differential transmission lines to no avail.

The differential transmission line impedance we are needing is in the range of
20-50 ohms.

We think the signal ground planes have minimal impact on the impedance of the
differential transmission line.

Any help/thought will be appreciated, and thanks a lot, ahead of time.

Ralph Hersey
Lawrence Livermore National Laboratory
e-mail:  [log in to unmask]

If possible "cc" (close copy) your response to:

Jim Zumstein
e-mail:  [log in to unmask]