LTspice chain of LC resonators

Discussion in 'Analog & Mixed-Signal Design' started by Partyzoa, Apr 9, 2017.

  1. Partyzoa

    Thread Starter New Member

    Apr 9, 2017
    3
    0
    Dear all,

    I am new to this forum and I really hope I posted this into the right place.
    On a way to solve a problem for my mathematical-physics class I tried to solve simple circuit with LTspice (picture below). upload_2017-4-9_20-29-24.png
    As a result I get 0V everywhere. What is wrong?

    Thank you for your time!
     
  2. crutschow

    Expert

    Mar 14, 2008
    19,528
    5,445
    What is the current direction of the two inductors (run the cursor over them to determine that).
    You may have them going against each other, which would cancel them.
     
    Last edited: Apr 9, 2017
  3. Bordodynov

    Well-Known Member

    May 20, 2015
    1,816
    547
    See
    Draft441.png
     
  4. Partyzoa

    Thread Starter New Member

    Apr 9, 2017
    3
    0
    Hello again,

    Thank you but something is still not working;
    I selected skip initial operating point solution and this showed:
    upload_2017-4-10_19-15-6.png

    upload_2017-4-10_19-16-0.png

    WARNING: Node N003 is floating.

    Per .tran options, skipping operating point for transient analysis.
    Singular matrix: Check node n002
    Iteration No. 1
    Fatal Error: Singular matrix: check node n002
    Iteration No. 1

    This circuit has floating nodes.

    Hope I did everything correct. Thank you for your time again!
     
  5. crutschow

    Expert

    Mar 14, 2008
    19,528
    5,445
    I had problems with the simulation also. I could not get it to work as Bordodynov did.
    It appears to not like setting initial current in an inductor in series with a capacitor.
    So in my simulation below I added switches to momentarily short the capacitor at the start of the simulation.
    The simulation then seems to work normally.

    upload_2017-4-10_10-44-56.png
     
  6. Bordodynov

    Well-Known Member

    May 20, 2015
    1,816
    547
    I have assigned the initial voltage on capacitor in most capacitor. This to value of the capacitor is added ic=0.
     
  7. crutschow

    Expert

    Mar 14, 2008
    19,528
    5,445
    Interesting technique.
    I haven't use the IC=0 with a capacitor before but it certainly works to give a proper simulation for this circuit.
     
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