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Id – Vds

by Dr. Rishi Todani & Dr. Ashis Kumar Mal

Plotting Id Vs. Vds for NMOS transistor is very similar to plotting id- vgs curve. First we draw the same schematic as in id-vgs, assign values to the variables, select the same outputs. The only difference would be that in dc analysis, instead of sweeping the voltage source connected to gate, we will select the voltage source connected to the drain of the transistor. Thus we will be sweeping Vds, i.e. Vds would be the X-axis and Plotting Id on the Y-axis.

This plot thus shown the plot for Id Vs. Vds for a given value of Vgs.

Parametric Analysis

Just like the parametric analysis of Id Vgs curves with various values of vds, we can perform parametric analysis of Id Vds curve with various values of Vgs. For this we select Vds as the sweep variable in DC analysis of Analog environment and we select vgs as the parametric variable of parametric analysis. The parametric window is as shown below.

Simulation can then be started by choosing Analysis > Start. The waveform will be as shown below.