Re: [SI-LIST] : Dual Stripline impedance

alterra@adnc.com
Fri, 17 Apr 1998 07:49:17 -0700

Magnus,

Using Ansoft's 2D Parameter Extractor I calculated the impedance matrix (low
frequency limiting values) as

Z11 = Z22 = 72.08 ohms
Z12 = 23.45 ohms

Since this line is symmetrical, the differential impedance is:

Zdiff = 2(Z11 - Z12)

which in this case gives a value of 97.3 ohms in agreement with the earlier
calculation from Vinu Arumugham.

Best regards,

Eric

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Eric Wheatley Ph.D. Electromagnetic Modeling Services
Alterra Technology Co. (760) 942-9426 (phone)
435 Dunsmore Ct. (760) 942-2366 (fax)
Encinitas, CA 92024 US alterra@adnc.com
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At 10:59 AM 4/17/98 +0200, you wrote:
>> For 1.4 mil Cu, 5 mil lines and a dielectric constant of 4.5, the
>> Synopsys (Viewlogic ADG ) field solver gives
>>
>> Zdiff ~ 97 ohm for:
>>
>> Plane
>> -----------------------
>> 14 mil
>>
>> --------
>> | L1 |
>> --------
>> 10 mil
>> --------
>> | L2 |
>> --------
>>
>> 14 mil
>> -----------------------
>> Plane
>>
>
>Thanks for this info!
>
>I finally find a demo version of Linpar from Artech House. I tried to
>analyze the setup above, and as a result I got an impedance matrix.
>However, I can't figure out how to get the differential impedance from
>that matrix. It's probaly really trivial, but...
>
>In another post I got the tip that I should try insertinga ground plane
>halfway in the structure. I tried that also, and got the Z at 57 ohms.
>It doesn't seem to be very accurate, does it?
>
>Any comments from you SI experts out there?
>
>