MPF102 IDSS Calculation

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

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
    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


    Dec 20, 2007
    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.
    tracecom likes this.