In the circuit below left, find value for R that results in VD = 0.7V. Assume k = 1.6mA/V2 and VTH = 0.5V. Another identical MOSFET is added as shown on right. Find the current ID2. Note that ID2 does not depend on the resistor value in the drain of Q2 as long as it is in saturation.
A simplified version of a cascode current source is shown below. Use LTspice to find the output resistance of the source and the minimum current source voltage Vcs,min. All four MOSFETs are identical. Use the following Spice directive for the MOSFETs. In addition to your value of Rout and Vcs,min your response to this problem should include a screen grab of your LTspice circuit and a plot of the drain current of M4 versus the current source voltage VCS. .model CCC NMOS level=1 vto =0.7 kp=5e-4 lambda=0.02 W=1e-6 L=1e-6 Be sure to replace the label NMOS beside the MOSFET with the label CCC in your LTspice circuit. This applies to all four MOSFETs in the circuit. Otherwise the circuit will not simulate accurately.