John,

If you refer your customer to the equations for stripline and microstrip
(or better show a drawing), hopefully, it'll become clear that it's ALWAYS
THE CASE.  Examine the equations to find out how the dielectric "constant"
and distance..etc would affect the impedence.
A good reference that I've used is Motorola's MECL design databook.  The
last one I looked at was a 1989 book.  Not sure if there is a newer
version!!  If anyone out there knows of a newer version, please LET ME
KNOW.  Thanks.

Groovy got me hooked on this book a while back.  thanks Groovy.

bilal khalaf




>This controlled impedance stuff is new to us...
>
>All the reading I have done seems to imply that reference planes are
>adjacent to the signal plane.  Is this typically the case, or always the
>case?
>I have a customer who keeps submitting designs which call for a controlled
>impedance line where the reference plane is not adjacent.
>
>Any input in helping us understand this would be appreciated.
>
>Regards