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  1. #1
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    Does this MOSFET work in "linear" or "saturation" region?

    Hi,

    The electronic load shown in attached image is constructed using a power mosfet Q1 (IRF540). Let's say the opamp MAX480 is powered by a 9V battery, thus the maximum output voltage of the opamp should be no more than 9V. If the load current is 10A, the voltage drop across the R10 resistor is 0.1x10=1.0V. If it's a 12V load, then the Vds=12-(0.1x10)=11V. To conduct current, the Vgs must be larger then Vth of the power mosfet. In this case, the Vds>(Vgs-Vth) and the power mosfet should be operating in "saturation" region. However, the power mosfet is said to act like a voltage controlled variable resistor (in "linear" region) in several articles. Which one is correct?

    Thanks.


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  2. #2
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    Re: Does this MOSFET work in "linear" or "saturation" region?

    for the mosfet circuit given by you ,
    the mosfet opeartes in 'saturation' region. you are right.

    but the circuit is operating in 'linear' region.

    to be clear , the device is in saturation but the circuit as a whole is in linear.


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