Figure 4

4.   Consider the current mirror shown in Figure 4

  • What is the output current Io?

  • What output voltage Vo is required to keep N2 in saturation?
    • Use the transistors described in the Widlar current mirror problem.

    Answer

    Using transistor parameters

    Equating current through the resistor to current through the transistor and solving for the gate to source voltage, V

    Where the quadratic formula has been used


    Solving for the current


    For N2 to remain in saturation (constant current region)