Question

2) Next generate a plot for Ip vs Vos for the diode connected NFET over 0-3 V of VDS bias. Include on your plot the effect of a bulk voltage of

-0.5, 0, 0.5 and 1V. The easiest way to get all 3 curves on the same plot is to use 3 instances of the device in your simulation schematic, each with different bulk bias voltages. Using NET aliases can be useful here. Repeat for our PFET but now with bulk bias voltages of 3.5, 3, 2.5 and 2V. Here you should clearly see the body effect on the transistor characteristic. Replot these for the square root of ID vs VGs and estimate the effective threshold for each bulk voltage. For the NFET a) Schematic used for the simulation b) Plot showing the simulation results for ID vs VGs for the different bulk voltages. c) Plot of the square root of ID vs VGS for the different bulk voltages. d) A table showing the threshold voltages vs the bulk bias Then include the same for the PFET. (need the screenshots for these) General observations and suggestions: be sure you have a proper ground or the simulator will not work, it needs to be set as node zero. Setting the bias will be a challenge for many of you. Think about the meaning of the sign of the current. To make the PFET plots look "normal" you can change the signs of the voltages and currents plotted as appropriate. Use enough points in your simulation to make the curves look smooth. Note: clearly label the axes, label the traces with the Vgs or bulk bias voltages used, also make the traces thicker than the default and adjust colors for readability. Be careful in your choice of NFET3 or NFET4, only use the 3 terminal version if you are sure that the source voltage will always be at ground for the NFET. The NFET3 and PFET3 versions have their source and bulk terminals tied together internally. For our process this cannot be done for the NFET but it can for the PFET.

Fig: 1