# [SI-LIST] Re: Need a equation of inductance calculation for microstrip over the ground plane

• From: Cristian Gozzi <cristian.gozzi@xxxxxxxxx>
• To: Charles.Grasso@xxxxxxxxxxxx
• Date: Tue, 23 Sep 2014 17:16:54 -0700

```Really nice tool :-)
I was not aware of it

Thanks a lot for sharing it...

Cris

2014-09-23 7:39 GMT-07:00 Grasso, Charles <Charles.Grasso@xxxxxxxxxxxx>:

> Saturn has a free PCB toolkit that reports transmission line properties.
> Its equation driven - but within its constraints
> might give you what you need.
> Best Regards
> Charles Grasso
> Compliance Engineer
> Echostar Communications
> (w) 303-706-5467
> (c) 303-204-2974
> (t) 3032042974@xxxxxxxxx
> (e) charles.grasso@xxxxxxxxxxxx
> (e2) chasgrasso@xxxxxxxxx
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of alfred1520list
> Sent: Wednesday, September 17, 2014 11:18 AM
> To: Dave Cuthbert
> Cc: C.C. Hwang; çææ¾; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Need a equation of inductance calculation for
> microstrip over the ground plane
>
> Ah, it is obvious, the delay is for the entire length of the transmission
> line. Sorry for the noise.
> On September 17, 2014 8:35:04 AM PDT, Dave Cuthbert <
> telegrapher9@xxxxxxxxx> wrote:
> >The capacitance is the total capacitance of the t-line. Knowing the
> >effective relative dielectric constant and the line length you can
> >calculate the propagation delay.
> >
> >To check that you have calculated the correct L and C, run it thru the
> >formula Z = (L/C)^0.5 and Z should be the characteristic impedance.
> >
> >  Dave Cuthbert
> >
> >On Wed, Sep 17, 2014 at 8:57 AM, alfred1520list
> ><alfred1520list@xxxxxxxxx>
> >wrote:
> >
> >> Hi Dave,
> >>
> >> Nice to know. Thanks.
> >>
> >> Does length play a part? Is it per unit length? What unit? Thanks.
> >>
> >> Best regards
> >> Alfred
> >>
> >> On September 17, 2014 5:57:16 AM PDT, Dave Cuthbert <
> >> telegrapher9@xxxxxxxxx> wrote:
> >>>
> >>> Song, here are my two favorite SI formulas (that's pretty geeky I
> >know):
> >>> C = t/Z
> >>>
> >>> L = t x Z
> >>>
> >>> The capacitance of a t-line (microstrip in your case) is the
> >propagation
> >>> delay divided by the line characteristic impedance.
> >>>
> >>> The inductance of a t-line is the propagation delay multiplied by
> >the line
> >>> characteristic impedance.
> >>>
> >>> Let's say you have a 50 ohm line and the propagation delay is 100
> >ps. The
> >>> capacitance is 2 pF and the inductance is 5 nH.
> >>>
> >>>    Dave Cuthbert, Narte Certified EMC Engineer
> >>>    Consultant for EMC, SI, RF, Power Electronics, and most
> >everything analog
> >>>
> >>> On Tue, Sep 16, 2014 at 9:22 PM, C.C. Hwang <cchwang2013@xxxxxxxxx>
> >wrote:
> >>>
> >>>  You can use a 2D solver (such as http://ataitec.com/free_2d_solver)
> >to
> >>>>  compute all RLGC.
> >>>>  Carl
> >>>>
> >>>>  On Sun, Sep 14, 2014 at 4:42 PM,
> ><wangwensong1986@xxxxxxxxx> wrote:
> >>>>
> >>>>  Hello everyone,
> >>>>>  Now I want to calculate a approximate value for inductance of
> >microstrip
> >>>>>  line over a ground plane.
> >>>>>
> >>>>>  Anyone have any references you can send my way? I know I've been
> >able to
> >>>>>  find this stuff in the past, but right now I'm coming up empty...
> >>>>>
> >>>>>  Thank you.
> >>>>>
> >>>>>  All the best,
> >>>>>
> >>>>>  Song
> >>>>>
> >>>>>
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> >>
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