MPF102 IDSS Calculation

Discussion in 'General Electronics Chat' started by tracecom, Oct 29, 2012.

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
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    From the data for Sample #1 in the attached chart and schematic, can IDSS be calculated? If so, please show me the math. Thanks.
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    IDSS is when the gate is connected to the source. But your circuit is different.
    It biases the source at a voltage higher than the gate so the Jfet is partially turned on with a "IDQ" which is its quiescent current, its Q-point.

    Look at the huge range of IDSS in its datasheet, from 2mA to 20mA. Each one is different.

    I think you want to calculate the quiescent current when the IDSS of the Jfet is many different values.

    The datasheet does not have enough information to accurately calculate it.
     
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