[SOLVED] MOSFET instead of planar resistors

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Zak28

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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.

 
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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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    Zak28

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What feedback arrangements are there without high speed opamps?
 

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