[SI-LIST] : Transmission line inductance

Josip Popovic (jpopovic@cmetele.com)
Thu, 25 Mar 1999 09:54:26 -0800

I would like to now if anyone of you had to create a PCB trace with a
precise inductance value?

In the spec for LT1533 (Linear Technology switching regulator) is shown
that
the device should have 25nH inductance between the ground pin and the
PCB
GND. According to my calculations a microstrip line with W=7 (H=5, T=2.8
and
Er=4.3) has app. 6.5nH/inch. So to get a 25nH trace one would need to
have a
3.8inch long trace.

Q1: Is there a trace configuration that I could use to create a 25nH
inductance that would not be so lengthy and in the same time would not
act
as an antenna?

Q2: Is my calculation (app 6.5nH/inch) correct?

Josip

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