coupled microstrip lines - RF Cafe Forums

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greggd
Post subject: coupled microstrip lines
Unread postPosted: Mon May 24, 2004 2:09 pm
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Joined: Mon May 24, 2004 1:56 pm
Posts: 1
Location: Moorestown, NJ
Does anyone have any tricks for optimizing coupled microstrip lines for differential mode (Zodd=50ohms, Zeven=100ohms)? I find that the closed form models in ADS and AWR do not match what is produced in Sonnet or Momentum.

Thanks for any help,

-Gregg

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Guest
Post subject:
Unread postPosted: Tue May 25, 2004 9:03 am

Sonnet and Momentum are "2.5D" simulators, the conductors must be zero thickness. Are you accounting for this? Momentum lets you define conductor thickness only for signal attenuation calculations not for geometric impact on electrical performance. Finite conductor thickness will have an effect on the odd mode impedance.

To my understanding, the "closed form" solver in LineCalc of ADS is a curve match to emperical and 3D simulated data for coupled lines. I have found it to be accurate enough for most edge coupled filters, as well as much faster than a MOM solver.

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guestX
Post subject: agreement
Unread postPosted: Tue Jun 01, 2004 2:47 am

The differential issue does not work properly in AWR. Sonnet seems to be closer. anyway, measure and compare it.
I came to 98% agreement with hand-calculation on 200ohm diff TL. The vector analyzer measure single ended parameters, then it converts to diff. Do you want the formula for conversion?

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