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 Fingers and multiplier of MOSFET 

Last post Fri, Apr 12 2013 1:13 AM by Gangadhar Redd. 4 replies.
Started by jun1119 27 Oct 2010 05:43 AM. Topic has 4 replies and 10594 views
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  • Wed, Oct 27 2010 5:43 AM

    • jun1119
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    Fingers and multiplier of MOSFET Reply

    Hi 

    What is the meaning of finger and multiplier in a MOSFET as we can see in the properties of a MOSFET?



     

    I would highly appreciated if there are some diagrams and layout to be shown.

    Thank  you

    • Post Points: 35
  • Wed, Oct 27 2010 6:30 AM

    • baenisch
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    Re: Fingers and multiplier of MOSFET Reply

     Hi there

     I have no idea what the multiplier does, in fact if have never used this at all in 16 years.

    The finger parameter on the other hand is very helpful if you want to draw big transistors.

    Changing the finger parameter simply creates parallel transistor gates to exactly the amount  you

    have entered.  Image you have a device in the schematic 400u wide but you don't have 400u

    of space in either direction but you have a nice little rectangular spot left. You create a single

    transistor 20u wide and change the finger parameter to 20. This yields in a 400u transistor

    with 20 "fingers" a 20u, drain/source areas already merged. You just have to do the wiring.

    Simply try it !

     

    Best Regards

     

    Andi

     

    • Post Points: 20
  • Thu, Oct 28 2010 4:56 AM

    • berndf
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    • Landshut, Bavaria
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    Re: Fingers and multiplier of MOSFET Reply

    This depends in the implementation of these parameters

    In most cases I have seen
    - number of fingers is a pysical paramter which lets you fold
      your mos width a long with to several mos with width/finger
      and shared S/D areas.
    - the m is a multiplication factor for the simulator which
      multiplies the current though the devices.

    Bernd

    • Post Points: 20
  • Mon, Nov 1 2010 12:38 PM

    • vvacad
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    Re: Fingers and multiplier of MOSFET Reply

    Hi,

    The m is the multiplication factor.

    In Layout XL, for transistors, the m from the schematic is used to create multiple layout instances with common parameters.

     i.e. for eg., a schematic instance M0 with total_width=6u, length=1u, fingers=3 finger_width=2u m=5

    will result in 5 layout instances:

    M0.0: total_width=6u, length=1u, fingers=3 finger_width=2u

    M0.1: total_width=6u, length=1u, fingers=3 finger_width=2u

    M0.2: total_width=6u, length=1u, fingers=3 finger_width=2u

    M0.3: total_width=6u, length=1u, fingers=3 finger_width=2u

    M0.4: total_width=6u, length=1u, fingers=3 finger_width=2u

    Rgds,

    Vikram

     

    • Post Points: 5
  • Fri, Apr 12 2013 1:13 AM

    • Gangadhar Redd
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    Re: Fingers and multiplier of MOSFET Reply

    Multiplier - number of Parallel MOS devices


    Finger Width - width of each gate finger/stripe


    Fingers - number of poly gate fingers/stripes used in layout

    Thanks & Regards Gangadhar.R
    • Post Points: 5
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Started by jun1119 at 27 Oct 2010 05:43 AM. Topic has 4 replies.