Re: [SI-LIST] : Transmission line inductance

Philip Gantt (pgantt@cisco.com)
Thu, 25 Mar 1999 14:20:12 -0800

I would suggest using a spiral shaped trace to increase the inductance.

Josip Popovic wrote:

> 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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Philip R. Gantt   pgantt@cisco.com                .           .
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