Allegro/Orcad Pspice current sources in series

Discussion in 'Electronics Resources' started by krishk24, Mar 16, 2008.

  1. krishk24

    Thread Starter New Member

    Mar 15, 2008
    2
    0
    Hi
    I am trying to simulate a ckt from a research paper using Allegro pspice schematic capture. i am running into a problem when i place current sources in series. current sources with different dc values in series violate KCL.

    even with the same current source value for both current sources, Pspice complains that nodes are floating.

    how do i resolve this issue ? see attached jpg for more information. the 2 current sources of interest are I5,I6.

    any help or thoughts appreciated.

    thanks
     
  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    Put a very high value resistor from the floating node to the ground. It would not affect the analysis.

    As for putting two current sources in series with different current values, it is not really possible.
     
  3. krishk24

    Thread Starter New Member

    Mar 15, 2008
    2
    0
    I am not sure if putting a high value resistor would solve my problem. the reason is there is actually NO phyiscal floating node since all the sources are with proper ground 0 reference.

    this problem happens when 2 current sources are in series (even with same value). current sources in series but with same value should work.

    if i remove 1 current source from the schematic, there are no errors.
     
  4. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    Try connecting the resistor from the node that's connected to the drain of one of the MOSFET to the ground. If the SPICE still complains about floating node, then copy the output file and post it here.
     
  5. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    Current sources in series should *not* work regardless of the current
    value.

    Use superposition. Place two current sources in series what is the voltage across either one?

    (* jcl *)
     
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