help with circuit synthesis

Discussion in 'Homework Help' started by Andrijana Kuhar, Jun 17, 2015.

  1. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
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    Hello :)

    I could really use some opinions on this :)
    I have the rational function of the input impedance of the circuit I need to design (in terms of angular frequency, W), but I am not really sure that it can be designed :( . I will write the impedance simplified here:
    Zin(jW)=((2-3j)/(jW+4-5j))+((2+3j)/(jW+4+5j))

    Any thoughts on which elements to use in the corresponding circuit?
    thank you in advance,
    best regards,
    Andrijana
     
  2. Veracohr

    Well-Known Member

    Jan 3, 2011
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    75
    I don't recall the 'proper' method at the moment, but start by simplifying the formula by combining the two rational sections. Then plot the equation across a frequency range and analyze its characteristics. Consider how the characteristics of the input impedance translate to the circuit's output characteristics. From that you should be able to determine the components and values.
     
  3. djb

    Member

    May 17, 2008
    18
    0
    In theory can be designed. This will lead to resistor and / or coil and or capacitor.
    In order to find the sizes of all that we must know the frequency of operation. These values are a function of frequency.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,003
    3,232
    Seems like this should be in homework.
     
  5. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
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    thank you for your answers. I need to make a circuit from real elements, so, the capacitor, coil and resistor must not be a function of frequency. any thoughts?
     
  6. ramancini8

    Member

    Jul 18, 2012
    442
    118
    Not sure your transfer function can be implemented as written. How do you get j and jw in the same term?
     
  7. Veracohr

    Well-Known Member

    Jan 3, 2011
    550
    75
    It can be implemented, I worked it out for myself yesterday. Just simplify the equation. It's a very simple circuit.
     
    Andrijana Kuhar likes this.
  8. WBahn

    Moderator

    Mar 31, 2012
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    MOD NOTE: This appears to be homework. Moved to Homework Help from General Electronics Chat.
     
  9. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
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    Could you explain in more details and maybe show the simple circuit? thanks!
     
  10. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
    14
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    this is a theoretically obtained impedance. the reason I posted this question is that I am not sure that there is a circuit, too :)
    thanks
     
  11. Veracohr

    Well-Known Member

    Jan 3, 2011
    550
    75
    Did you simplify the equation and plot it?

    My method probably isn't what your teacher had in mind. I vaguely remember some kind of formal approach to circuit synthesis from a function but I'd have to look it up to remember.
     
  12. WBahn

    Moderator

    Mar 31, 2012
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    For "real" components, the values almost always ARE a function of frequency. We often assume that they aren't (i.e., assume that we have "ideal" components) to make the math a lot easier and that assumption is usually good enough.
     
  13. WBahn

    Moderator

    Mar 31, 2012
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    Could you show some effort to at least attempt to solve your own homework?
     
  14. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
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    is this the way you "solve" problems when you don't know how to actually solve them? thanks a bunch
     
  15. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
    14
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    I know where the poles are, I just can't find a circuit to match those poles :/
     
  16. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
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    the circuit is supposed to be solved with spice, so , yes, i need "real" components, and not REAL components.
     
  17. WBahn

    Moderator

    Mar 31, 2012
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    1) It's not MY job to solve it -- it's YOUR homework.

    2) I'm more than willing to help you walk through the problem, but you want someone to carry you from start to finish.

    3) Your little mind games don't play too well around here. We've seen this "prove you can solve it" trick used way too many times.

    You're welcome.

    When you decide you want to show some effort, we can continue. Until then, I'll focus on those that are willing to at least try.
     
  18. Andrijana Kuhar

    Thread Starter New Member

    Jun 17, 2015
    14
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    I thought this was a forum where people actually solve circuit problems, but hey, it's not YOUR job to solve MY problem :D
    thank you so much for the life wisdom that you gave me :)
     
  19. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
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    It is. Homework is entirely different. Trying to get your homework done for you in the other area's rarely work. The rules of the homework area are clearly posted ... http://forum.allaboutcircuits.com/t...ng-questions-in-the-homework-help-forum.3002/ ... which is why you went into another area to dupe someone into doing your homework.
     
  20. WBahn

    Moderator

    Mar 31, 2012
    17,737
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    The sad part is that I believe you really do think that this is a place where it is okay to expect other people to do your homework for you without you making the slightest effot.

    If you found out today that the doctor you were considering going to never did any of his own work in medical school but rather found someone else to do it for them, would you still choose to go them?

    Maybe that is the way things are done where you're from.
     
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