+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Advanced Member level 3
    Points: 5,479, Level: 17
    Achievements:
    7 years registered

    Join Date
    Jan 2012
    Location
    Italy
    Posts
    957
    Helped
    41 / 41
    Points
    5,479
    Level
    17

    devideing large MOSFET gate using muti fingers

    Dear friends,

    it is usually preferable to divide large MOSFET to some number of gate fingers to reduce the channel resistance, also there is other advantages when we use even number of gate fingers to reduce the drain area and hence improve the AC characteristics. However in analog circuit design I believe that there must be a price of this operation.

    Therefore I would like to ask you please about the side effects of dividing the transistor using large number of fingers, what is the maximum division I should do ?

    Thank you very much

    •   AltAdvertisement

        
       

  2. #2
    Full Member level 1
    Points: 1,388, Level: 8

    Join Date
    Mar 2015
    Location
    USA
    Posts
    111
    Helped
    20 / 20
    Points
    1,388
    Level
    8

    Re: devideing large MOSFET gate using muti fingers

    Two things that immediately come to mind are that you donít want to make the devices so small that matching suffers. You also donít want to make them so small that you canít contact enough metal on the stripes to meet electromigration requirements.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 3
    Points: 5,479, Level: 17
    Achievements:
    7 years registered

    Join Date
    Jan 2012
    Location
    Italy
    Posts
    957
    Helped
    41 / 41
    Points
    5,479
    Level
    17

    Re: devideing large MOSFET gate using muti fingers

    Dear ljp

    thank you for your reply,

    if I am using channel length of 1 um. and I go down to 0.5 um/1 um, is this considered small ?

    thank you



    •   AltAdvertisement

        
       

  4. #4
    Full Member level 1
    Points: 1,388, Level: 8

    Join Date
    Mar 2015
    Location
    USA
    Posts
    111
    Helped
    20 / 20
    Points
    1,388
    Level
    8

    Re: devideing large MOSFET gate using muti fingers

    That depends on what process node youíre working in. What is the minimum feature size in the process youíre working in? Also, your pdk will have a section on matching. That should provide additional guidance regarding how small is acceptable for your application.


    1 members found this post helpful.

  5. #5
    Advanced Member level 3
    Points: 5,771, Level: 18
    Dominik Przyborowski's Avatar
    Join Date
    Jun 2013
    Location
    Norway
    Posts
    755
    Helped
    318 / 318
    Points
    5,771
    Level
    18

    Re: devideing large MOSFET gate using muti fingers

    Read information about "narrow width effects"


    1 members found this post helpful.

--[[ ]]--