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

• From: alfred1520list <alfred1520list@xxxxxxxxx>
• To: Dave Cuthbert <telegrapher9@xxxxxxxxx>
• Date: Wed, 17 Sep 2014 10:18:04 -0700

```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, ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
><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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>> --
>> Sent from my Android phone with K-9 Mail. Please excuse my brevity.
>>

--
Sent from my Android phone with K-9 Mail. Please excuse my brevity.

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