common source mosfet in pspice

Discussion in 'Homework Help' started by darklord_V, Sep 7, 2011.

  1. darklord_V

    Thread Starter New Member

    Sep 7, 2011
    how can i make a common source mosfet circuit so that i can plot its characteristics graph??
    i am completely noob at using pspice.
  2. Adjuster

    Well-Known Member

    Dec 26, 2010
    To obtain the usual family of IDS vs VDS curves with VGS as a parameter, two voltage sources are required, one for the gate, the other for the drain.

    You require a common-source circuit, where the source is a connection common to the input and the output circuits. This is often thought of as a a grounded point, although this is not always strictly true in practice. Since a ground reference is required in Spice simulations, it is convenient to join the source to ground in this example.

    The source of the FET and one side of each of the two voltage sources are therefore returned to ground. The polarity of the sources depends on the FET type, but for the most usual enhancement N-channel MOSFET both the voltages need to be positive with respect to ground.

    With a current probe placed at the drain, a DC sweep of the drain voltage source over an appropriate range will provide an IDS vs VDS plot. If you need this for more than one value of VGS, place a parameter instruction to control the gate voltage supply, and take a parametric run with the gate voltage set to the values you require.