[SI-LIST] Re: Capacitance of Transmission Line

  • From: "icer world" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "icermail@xxxxxxxxx" for DMARC)
  • To: "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx>, "dmarc-noreply@xxxxxxxxxxxxx" <dmarc-noreply@xxxxxxxxxxxxx>, Si-list <si-list@xxxxxxxxxxxxx>
  • Date: Fri, 9 Jan 2015 06:08:56 +0000 (UTC)

Hi Charles,
Thanks very much. 
     On Friday, January 9, 2015 4:48 AM, "Grasso, Charles" 
<Charles.Grasso@xxxxxxxxxxxx> wrote:
   

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{}#yiv0871948057 Repost as my previous post was “scrambled” (at least on my 
machine).    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    From: Grasso, Charles
Sent: Thursday, January 08, 2015 9:16 AM
To: 'icer world'; dmarc-noreply@xxxxxxxxxxxxx; Si-list
Subject: RE: [SI-LIST] Re: Capacitance of Transmission Line    Hello, Based on 
your previous email and my (old) knowledge of Ansys Q3D my suspicion is simply
iterative solution deltas. You extracted the RLC for a trace over a plane and 
the two parameters
that *are* frequency dependent will the R and the L.  (I did not know that Q3D
calculated G as well) Unless Q3D can account for Er changes with frequency 
(which in old
revisions it could not and by the way are inconsequential in the frequency 
ranges you
are solving in) I suggest you extract the C independent of the other 
parameters. I recommend that call you contact your  local Ansys AE for better 
guidance.    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    From: icer world 
[mailto:icermail@xxxxxxxxx]
Sent: Wednesday, January 07, 2015 11:56 PM
To: Grasso, Charles; dmarc-noreply@xxxxxxxxxxxxx; Si-list
Subject: Re: [SI-LIST] Re: Capacitance of Transmission Line    Hi Charles,    
Thanks for your reply.    I used Q3D to do the extraction and the difference 
is 1pF. @100MHz, the capacitance is about 11.5pF, while 10pF @1GHz. Altough the 
difference is small, I still want to know why has this change.    On Thursday, 
January 8, 2015 5:28 AM, "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx> wrote: 
   Hi - two questions:
1. What is the delta between the differences?
And
2.  What is the tool are you using for the extraction?

I suspect you are seeing "rounding" errors from the simulation engine.


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 icer world
Sent: Wednesday, January 07, 2015 12:04 AM
To: Si-list
Subject: [SI-LIST] Capacitance of Transmission Line

Hi Experts,
Happy new year!
When I extract the RLCG of ideal transmission line, I observe that the 
capacitance varies in different frequency, although it's small. In my opinion, 
the capacitance should keep same when the frequency changes, because I set the 
relative dielectric constants same in all the frequency.
Could anybody help explain it ?
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