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Original question:

TINA/Spice/LMG1020: Need a spice model for LTspice, encrypted model doesn't work with LTspice

TINA/Spice/LMG1020: S parameters for LMG1020

Daniel Brolin
Prodigy 10 points
Part Number: LMG1020
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hello,

I have lately been working on simulating the capacitive and inductive losses in some of our PCB's. The last missing information would be the experimental/simulated S parameters of the LMG1020.

There is a way to generate the parameter file from LTspice, but since the simulationfiles are encrypted I can't use the spice files with LTspice. I have since downloaded Tina-TI, but doing a fast google search I can't seem find any guides on how to generate S parameters in Tina-TI.

Only having thesimulation files encrypted put some twigs in my wheels, but having no apparent alternative is a little annoying. Is it possible for you to directly email the measured S parameters, or send me a link to how I generate them from Tina-TI ?

Thank you in advance.


Best Regards,
Daniel Brolin

  • 0
    TI__Genius 9775 points
    Hi Daniel,

    Unfortunately TINA-TI does not have S-param capability. However, to extract any S parameters, you can follow the general S parameters theory:

    1. Establish the node/pin at the right operating point

    2. Then use the general sparameters equation assuming you're using 50 ohms termination:
    S = ( Z - 50 ) / (Z + 50)

    To get the Z value, for instance to get output or input impedance of certain node, then you can inject small signal current source (ac analysis as necessary) and then measure the return voltage. Then use Z = return voltage / current. If you set current on the ac analysis as "1" as usually it is for most simulation. Then your return voltage is equal to the "Z".

    FYI, Z is usually a complex number or outputted as (real, imaginary) and/or (magnitude, phase). So just make sure when you do number crunching together with (Z-50)/(Z+50), you take this into consideration.

    I usually convert the complex number into real and imaginary so that I can do the number crunching easier. So basically, my final S equation is as follow:

    sqrt(real( ("/Z") - 50)**2+imag( ("/Z") )**2) / sqrt(real( ("/Z") + 50)**2+imag( ("/Z") )**2)

    Herman