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    MOSFET instead of planar resistors

    Is it fine to employ to220/247/3P MOSFETs as resistors inplace of similarly packaged planar resistors for constant loads and for switched loads?

    The NMOS would be biased with a precision pot at its gate using a DMM from power supply to drain to make the current precise.

    Constant load.



    Switched load.

    Last edited by Zak28; 4th September 2019 at 06:07.

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    Re: MOSFET instead of planar resistors

    1. Don't expect stable current in this circuit due to temperature dependent Vgs/Id characteristic. Some kind of feedback suggested.
    2. Consider reduced power rating of MOSFET in linear mode caused by inhomogeneous current distribution. Check SOA in datasheet.


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  3. #3
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    Re: MOSFET instead of planar resistors

    Quote Originally Posted by FvM View Post
    1. Don't expect stable current in this circuit due to temperature dependent Vgs/Id characteristic. Some kind of feedback suggested.
    2. Consider reduced power rating of MOSFET in linear mode caused by inhomogeneous current distribution. Check SOA in datasheet.
    What feedback arrangements are there without high speed opamps?



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