Small signal model-need circuit verification

Discussion in 'Homework Help' started by sara yu, Nov 6, 2015.

  1. sara yu

    Thread Starter New Member

    Sep 24, 2015
    9
    0
    Hi
    I am not good at drawing small signal circuits from the given MOSFET circuits. But I tried for one circuit here, I need someone to verify it and correct me if I am wrong?
    2 attachments below has my answer in one and my unsure areas mentioned along with the question in the other.
    Thank you.


    IMG_2267_800x600.jpg

    IMG_2268_800x596.jpg
     
  2. sara yu

    Thread Starter New Member

    Sep 24, 2015
    9
    0
    Can someone please help me understand this...
    Can we always replace the diode connected MOSFET with a resistor (1/gm) or in small signal model?
    Also, Do we take gate voltage of the FET connected to the DIODE connected transistor as 0 if (1. same current flows through it(as it is in saturation), i.e constant voltage at that point= DC voltage= AC ground? 2. if that point is also connected to a DC source?)
    I have a MOSFET problem to solve and then do spice simulation of the same....to compare the results.(image attached)
    thank you in advance for any help or suggestions.

    FullSizeRender_800x600.jpg
     
  3. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    Please compress the file size to as 800x600 or 1024x768(if needed) before you attach them, the above files I already compressed to 800x600.
     
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