current mirror

Discussion in 'General Electronics Chat' started by Angeline, Aug 20, 2014.

  1. Angeline

    Thread Starter New Member

    Aug 20, 2014
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    MOSFET is a voltage controlled device..can current be given as inputs??
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Can you be more specific about what you have in mind ?
     
  3. pwdixon

    Member

    Oct 11, 2012
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    Drive the current into a resistor and it becomes a voltage, apply a suitable voltage to the MOSFET gate and voila. But if you are trying to detect current then this is not great as the power dissipated in the resistor may be quite high given the FET gate threshold voltage requirements.
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The MOSFET gate has significant capacitance which has to be charged/discharged to switch the FET on/off. This involves a burst of current.
     
  5. ian field

    Distinguished Member

    Oct 27, 2012
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    There are examples of MOSFET based current mirrors if you search hard enough.

    Generally speaking though, there's usually too much variation from one device to the next in VGSthr.
     
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