+ Post New Thread
Results 1 to 10 of 10
  1. #1
    Newbie level 1
    Points: 980, Level: 7

    Join Date
    Jun 2007
    Posts
    1
    Helped
    0 / 0
    Points
    980
    Level
    7

    s-parameter inductance

    Hi,

    I'm trying to determine the inductance and capacitance of chip inductors/capacitors at 1-2 GHz from the S-Parameters (S11 & S21) measured on an VNA. Does anyone know what equations/methods I should use to get these values. Thank you for your help!

    •   Alt29th June 2007, 21:14

      advertising

        
       

  2. #2
    Advanced Member level 1
    Points: 4,664, Level: 16
    radiohead's Avatar
    Join Date
    May 2004
    Location
    Heart of Europe
    Posts
    437
    Helped
    59 / 59
    Points
    4,664
    Level
    16

    capacitance from s parameters

    1. Find an appropriate model including the most important parasitics
    2. Find some good starting component values for the I/C and their parasitics
    3. Optimize the component value and parasitics (preferrably automatically) to the S-parameters match the model as good as possible.

    A good starting point for inductors would be the Spice models of the Coilcraft inductors. You should be able to find something similar for the caps, but usually a series RLC circuit works fine.

    http://www.coilcraft.com/models.cfm


    1 members found this post helpful.

  3. #3
    Advanced Member level 3
    Points: 16,944, Level: 31

    Join Date
    Aug 2005
    Location
    INDIA
    Posts
    810
    Helped
    228 / 228
    Points
    16,944
    Level
    31

    s parameter inductance

    Hello asubraman,

    Import or read your S-pareameter file to any simulator (AWR MWO or Sonnet EM)
    then plot the Y parameters Then use the following equation to get the Capacitance & Indutance values

    Y11 = Im(Y(1,1))

    C1=1.0E12 / ( 2 * _PI * _FREQ * ( 1 / Y11 ) )

    Where
    L1=1.0E9 * ( 1 / Y11 ) / ( 2 * _PI * _FREQ )

    L1: Effective Inductance (in nH) of a series RL network

    C1: Effective Capacitance (in pF) of a series RC network

    _FREQ: is project frequencies in GHz

    Note: Sonnet has direct measurement option for the above...


    ---manju---


    1 members found this post helpful.

  4. #4
    Junior Member level 2
    Points: 711, Level: 5

    Join Date
    Jan 2010
    Location
    India
    Posts
    23
    Helped
    1 / 1
    Points
    711
    Level
    5

    Re: Determining Inductance/Capacitance from S-Parameters

    dear manju,

    thank you so much for the above post, it really helped me. can u tell me whether in this case, the resistance would be Re(Z(1 1)) or Re(1/Y(1 1))?



    •   Alt6th April 2010, 10:53

      advertising

        
       

  5. #5
    Advanced Member level 4
    Points: 10,485, Level: 24
    kspalla's Avatar
    Join Date
    Aug 2008
    Location
    Hyderabad, Andhra Pradesh, India
    Posts
    1,249
    Helped
    243 / 243
    Points
    10,485
    Level
    24

    Determining Inductance/Capacitance from S-Parameters

    both should be equal by theory.



  6. #6
    Advanced Member level 3
    Points: 16,944, Level: 31

    Join Date
    Aug 2005
    Location
    INDIA
    Posts
    810
    Helped
    228 / 228
    Points
    16,944
    Level
    31

    Re: Determining Inductance/Capacitance from S-Parameters

    hello,


    I hope this helps you...see the attached document...

    ---manju---


    2 members found this post helpful.

  7. #7
    Junior Member level 2
    Points: 711, Level: 5

    Join Date
    Jan 2010
    Location
    India
    Posts
    23
    Helped
    1 / 1
    Points
    711
    Level
    5

    Determining Inductance/Capacitance from S-Parameters

    Dear Manju,

    In the calculation of L1, the formula you have used.... is it 1/imag(Y(1 1)) or should it be imag(1/Y(1 1))? Please reply soon... Thanks so much!

    Kas



  8. #8
    Advanced Member level 3
    Points: 16,944, Level: 31

    Join Date
    Aug 2005
    Location
    INDIA
    Posts
    810
    Helped
    228 / 228
    Points
    16,944
    Level
    31

    Re: Determining Inductance/Capacitance from S-Parameters

    Hello acekas,

    it is imag(1/Y11)...

    Also Note that on your query Resistance calculation;
    If you are looking for the equivalent series resistance then

    Z11 is only equal to 1/Y11 for a one-port (or if you short circuit port 2 device).
    When you have a two-port, Y and Z are matrices and you cannot just take the reciprocal of each element in the matrix.

    so whatever kspalla told was theoretically not true...

    I hope this helps you...!!!


    ---manju---


    1 members found this post helpful.

  9. #9
    Junior Member level 2
    Points: 711, Level: 5

    Join Date
    Jan 2010
    Location
    India
    Posts
    23
    Helped
    1 / 1
    Points
    711
    Level
    5

    Determining Inductance/Capacitance from S-Parameters

    Thanks Manju, yeah, that helped!

    Regarding what you said about short circuiting port 2, can you please tell me how I can do that on cadence?

    Further, isn't the expression imag(1/Y(1 1))... valid only for circuits with the second port short-circuited? If not, I would appreciate it tremendously if you could throw some light on how we are arriving at the expression!

    Thank you once again!
    Kas



  10. #10
    Full Member level 3
    Points: 1,193, Level: 7

    Join Date
    Feb 2012
    Location
    Tamilnadu, India
    Posts
    167
    Helped
    25 / 25
    Points
    1,193
    Level
    7

    Re: Determining Inductance/Capacitance from S-Parameters

    Quote Originally Posted by acekas View Post
    Thanks Manju, yeah, that helped!

    Regarding what you said about short circuiting port 2, can you please tell me how I can do that on cadence?

    Further, isn't the expression imag(1/Y(1 1))... valid only for circuits with the second port short-circuited? If not, I would appreciate it tremendously if you could throw some light on how we are arriving at the expression!

    Thank you once again!
    Kas
    can i do it in cadence?



+ Post New Thread
Please login