+ Post New Thread
Results 1 to 10 of 10
  1. #1
    Full Member level 4
    Points: 1,375, Level: 8

    Join Date
    Jan 2018
    Posts
    221
    Helped
    1 / 1
    Points
    1,375
    Level
    8

    Design pi/2 artificial transmission line using lumped elements

    Hi, I was reading the paper "Design Methodology for distributed Power Amplifier in Software -Defined Radio Applications" and came across
    "Once the characteristic impedances values are fixed, design can be completed by synthesizing the pi/2 transmission lines using lumped components and embedding the devices". I know how to make a transmission line using lumped elements but how do we do it for particular length of the line? Does it mean we need to design an inductor and capacitor per unit length and distribute them until we have pi/2 electrical length?

    •   AltAdvertisement

        
       

  2. #2
    Advanced Member level 5
    Points: 17,685, Level: 32
    pancho_hideboo's Avatar
    Join Date
    Oct 2006
    Location
    Real Homeless
    Posts
    2,721
    Helped
    739 / 739
    Points
    17,685
    Level
    32

    Re: Design pi/2 artificial transmission line using lumped elements

    Quote Originally Posted by circuitslave View Post
    I know how to make a transmission line using lumped elements
    I don't know how to make a transmission line using lumped elements.

    Teach me how to make a transmission line using lumped elements.

    Quote Originally Posted by circuitslave View Post
    "Once the characteristic impedances values are fixed,
    design can be completed by synthesizing the pi/2 transmission lines
    using lumped components and embedding the devices"
    .
    Simply it is a phase shifter of pi/2.



  3. #3
    Full Member level 4
    Points: 1,375, Level: 8

    Join Date
    Jan 2018
    Posts
    221
    Helped
    1 / 1
    Points
    1,375
    Level
    8

    Re: Design pi/2 artificial transmission line using lumped elements

    Quote Originally Posted by pancho_hideboo View Post

    Teach me how to make a transmission line using lumped elements.
    I don't believe if you say that you don't know something. You are genius. I can make lossless line using lumped elements. Connect Inductor in series and Capacitor in shunt and repeat the combination that gives artifical transmission line.

    Quote Originally Posted by pancho_hideboo View Post
    Simply it is a phase shifter of pi/2.
    I don't understand what do you mean by this



    •   AltAdvertisement

        
       

  4. #4
    Advanced Member level 1
    Points: 6,028, Level: 18

    Join Date
    Jul 2004
    Posts
    450
    Helped
    86 / 86
    Points
    6,028
    Level
    18

    Re: Design pi/2 artificial transmission line using lumped elements

    Look at ABCD parameters for lumped components and transmission line.



    •   AltAdvertisement

        
       

  5. #5
    Full Member level 4
    Points: 1,588, Level: 9

    Join Date
    Jan 2019
    Location
    Ireland
    Posts
    219
    Helped
    91 / 91
    Points
    1,588
    Level
    9

    Re: Design pi/2 artificial transmission line using lumped elements

    Quote Originally Posted by circuitking View Post
    I don't believe if you say that you don't know something. You are genius. I can make lossless line using lumped elements. Connect Inductor in series and Capacitor in shunt and repeat the combination that gives artifical transmission line.
    What he means is that you can only approximate a particular length of transmission line at a particular frequency by lumped components. Placing a length of transmission line only rotates your impedance on the Smith Chart and introduces a phase delay. And given full freedom in the choice of lumped components, you can match any (passive) load to another (passive) load. For example, one of the most common approximations of a lambda by 4 tline is a pi network but it works 'perfectly' only at one frequency.

    - - - Updated - - -

    Quote Originally Posted by pancho_hideboo View Post

    Simply it is a phase shifter of pi/2.
    pi/2 is the electric length I think.. Won't the phase shift be pi?

    - - - Updated - - -

    Quote Originally Posted by pancho_hideboo View Post

    Simply it is a phase shifter of pi/2.
    pi/2 is the electric length I think.. Won't the phase shift be pi?

    - - - Updated - - -

    Ignore the last part of the last message. I was thinking of something else when I typed that. Sorry about it. (somehow I misread pi by lambda)..

    A lambda by 4 TLIne introduces a phase shift of pi/2. It also transforms your impedance as Zo^2/ZL where Zo is the characteristic impedance of the line and Zl is the load impedance,



  6. #6
    Advanced Member level 5
    Points: 14,848, Level: 29

    Join Date
    Apr 2014
    Posts
    2,311
    Helped
    928 / 928
    Points
    14,848
    Level
    29

    Re: Design pi/2 artificial transmission line using lumped elements

    Quote Originally Posted by circuitking View Post
    I know how to make a transmission line using lumped elements but how do we do it for particular length of the line? Does it mean we need to design an inductor and capacitor per unit length and distribute them until we have pi/2 electrical length?
    Yes, your delay line from lumped components will have low pass characteristics. The more segments you use, the more it approximates the truely distributed LC of the line, for wider bandwidth.



  7. #7
    Advanced Member level 5
    Points: 17,685, Level: 32
    pancho_hideboo's Avatar
    Join Date
    Oct 2006
    Location
    Real Homeless
    Posts
    2,721
    Helped
    739 / 739
    Points
    17,685
    Level
    32

    Re: Design pi/2 artificial transmission line using lumped elements

    Quote Originally Posted by circuitslave View Post
    I can make lossless line using lumped elements.
    Connect Inductor in series and Capacitor in shunt and repeat the combination that gives artifical transmission line.
    It is not a transmission line.
    https://www.edaboard.com/showthread.php?385727#4



    •   AltAdvertisement

        
       

  8. #8
    Advanced Member level 5
    Points: 31,059, Level: 43
    BigBoss's Avatar
    Join Date
    Nov 2001
    Location
    Turkey
    Posts
    4,561
    Helped
    1374 / 1374
    Points
    31,059
    Level
    43

    Re: Design pi/2 artificial transmission line using lumped elements

    A Transmission Line can be represented and modelled by R-L-C-G elements.
    This page is available for everyone and the chapters can be downloaded.
    http://eceweb1.rutgers.edu/~orfanidi/ewa/

    Chapter 11-6 expresses this ..


    1 members found this post helpful.

  9. #9
    Advanced Member level 5
    Points: 17,685, Level: 32
    pancho_hideboo's Avatar
    Join Date
    Oct 2006
    Location
    Real Homeless
    Posts
    2,721
    Helped
    739 / 739
    Points
    17,685
    Level
    32

    Re: Design pi/2 artificial transmission line using lumped elements

    Quote Originally Posted by BigBoss View Post
    A Transmission Line can be represented and modelled by R-L-C-G elements.
    This page is available for everyone and the chapters can be downloaded.
    http://eceweb1.rutgers.edu/~orfanidi/ewa/

    Chapter 11-6 expresses this ..
    These are not lumped components.

    Rather https://www.edaboard.com/showthread.php?385427#2
    Last edited by pancho_hideboo; 28th July 2019 at 02:02.



  10. #10
    Full Member level 4
    Points: 1,588, Level: 9

    Join Date
    Jan 2019
    Location
    Ireland
    Posts
    219
    Helped
    91 / 91
    Points
    1,588
    Level
    9

    Re: Design pi/2 artificial transmission line using lumped elements

    If you want to see how increasing number of LC segments make a closer approximation to transmission line, check out this rather basic paper: https://ip.cadence.com/uploads/1012/...Final_0416-pdf



--[[ ]]--