Home > Community > Forums > RF Design > How to Model 40cm tline Using LMG Tool

Email

* Required Fields

Recipients email * (separate multiple addresses with commas)

Your name *

Your email *

Message *

Contact Us

* Required Fields
First Name *

Last Name *

Email *

Company / Institution *

Comments: *

 How to Model 40cm tline Using LMG Tool 

Last post Mon, Jan 10 2011 9:44 AM by Tawna. 5 replies.
Started by saurabhsant 09 Jan 2011 02:09 AM. Topic has 5 replies and 4455 views
Page 1 of 1 (6 items)
Sort Posts:
  • Sun, Jan 9 2011 1:35 AM

    Transmission Line Modelling in Cadence Reply

    Hi

    I want to model a 40cm FR4 line in Cadence using the parameters provided by manufacturer. I modelled a 4cm line using mtline model and LMG tool in it. A parameter of fmax is set to 18GHz as I have to operate at 16GHz. 

    When I tried to model a 20cm TLine, I received error message that, the tool cannot model lines with more than 5 wavelengths long. 

    Could somebody tell me how to model a 40cm transmission line in Cadence using given parameters? If yes, which tool does this sort of modelling? 

     Thanks in advance.

     

    • Post Points: 5
  • Sun, Jan 9 2011 1:39 AM

    Long Tramsmission Line Model in Cadence Reply

    Hi

    I want to model a 40cm FR4 line in Cadence using the parameters provided by manufacturer. I modelled a 4cm line using mtline model and LMG tool in it. A parameter of fmax is set to 18GHz as I have to operate at 16GHz. 

    When I tried to model a 20cm TLine, I received error message that, the tool cannot model lines with more than 5 wavelengths long. 

    Could somebody tell me how to model a 40cm transmission line in Cadence using given parameters? Which tool does this sort of modelling? 

     Thanks in advance.

    Filed under:
    • Post Points: 20
  • Sun, Jan 9 2011 2:09 AM

    How to Model 40cm tline Using LMG Tool Reply

    Hi

    I want to model a 40cm FR4 line in Cadence using the parameters provided by manufacturer. I modelled a 4cm line using mtline model and LMG tool in it. A parameter of fmax is set to 18GHz as I have to operate at 16GHz. 

    When I tried to model a 20cm TLine, I received error message that, the tool cannot model lines with more than 5 wavelengths long. 

    Could somebody tell me how to model a 40cm transmission line in Cadence using given parameters? Which tool does this sort of modelling? 

    Thanks in advance.

    Filed under: ,
    • Post Points: 20
  • Mon, Jan 10 2011 9:33 AM

    Re: Transmission Line Modelling in Cadence Reply

    Please do not post the same question in multiple forums. If it's in the wrong forum, we'll move it. You are merely likely to irritate people by posting in more than one place.

    I'll merge this with the same question in the RF forum (seems as good a place as any).

    Andrew.

    • Post Points: 20
  • Mon, Jan 10 2011 9:44 AM

    Re: Transmission Line Modelling in Cadence Reply

    My guess is that you're using the standalone "lmg" tool (from the question). If so, this is obsolete and should not be used.

    Instead, place an instance of the "mtline" component from analogLib, and choose the Type of Input as being "Field Solver". Then enter the physical parameters about the line in the property fields for mtline - you can still press "Display Cross Section" to visualize it.

    The benefit of this approach is that the solver is run within the simulator, and generates the RLGC matrices (which are per-unit-length, and so do not have a length limitation). Because it's done in the simulator, you can parameterize the line's physical parameters, and sweep them, and so on.

    With lmg, you could choose to produce either a lumped model or RLGC parameters. The lumped model had to know the physical length of the line, because otherwise it couldn't lump it - and this had limitations on the length of the line.

    Since lmg has not been maintained, it will not have any of the improvements or fixes in the built-in field solver which is part of mtline. So you really should use that.

    Best Regards,

    Andrew.

    • Post Points: 5
  • Mon, Jan 10 2011 9:44 AM

    • Tawna
    • Top 25 Contributor
    • Joined on Thu, Jul 10 2008
    • Snohomish, WA
    • Posts 212
    • Points 5,625
    Re: Long Tramsmission Line Model in Cadence Reply

    Hi Saurabhsant,

    Do not use LMG .  It is no longer supported and hasn't been updated (fixes, enhancements) in a number of years.   If mtline isn't working, you may need to look at the nport.   Please see the following Cadence On Line support solutions:

     

    The mtline appNote:

    http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:doc;src=wp;q=ApplicationNotes/Custom_IC_Design/mtlineAN.pdf 

    Nport appNote:

    http://support.cadence.com/wps/PA_DocumentViewer/solution/11112746/NportAppNote72_8Jan.pdf

    If you are using mtline with significant skin effect and dielectric loss at high frequency, you will need to use the workaround in Cadence On-line Solution 11684156.

    Otherwise you may get incorrect results.   

     fmax (nport or mtline) needs to be set to the highest frequency of interest (this includes harmonics.   I suspect you need to set this higher.

    best regards,

    Tawna

    Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
    • Post Points: 5
Page 1 of 1 (6 items)
Sort Posts:
Started by saurabhsant at 09 Jan 2011 02:09 AM. Topic has 5 replies.