NMOS as an Inverter (Switch)

In this lab you will initially simulate an NMOS (2N7000) using Multisim and its DC sweep and then apply the same procedure in the implementation of the circuit.

Part 1: Simulation:

  1. Build the circuit in Figure 1 in Multisim. Choose an arbitrary value for V1. It is not important. Go to Simulate>>Analyses>>DC sweep. In "Analysis parameters" tab select V1 as the source and 0V as Start value, 5V as Stop value in 0.1V increments. Now select "Output tab" and add V1 and the voltage corresponding to drain. Click on "Simulate". You should get a graph of drain voltage as V1 sweeps from 0 to 5V. Start a MS Word document and include this graph and all the indicators as what this graph and values used were. What is the threshold voltage?

    Figure 1 - NMOS Inverter Circuit 1
  2. Build the circuit in Figure 2 in Multisim and repeat the procedure in Part 1, a. Again, include the resulting graph and all the indicators in your report. As you look at the two graphs, what is your observation and why?

    Figure 2 - NMOS Inverter Circuit 2

Part 2: Implementation:

  1. Build the circuit in Figure 1 on your breadbord. For VDD use the +25V output and for V1 +6V of your power supply. Start from 0 for V1 and increase the value by 0.2V each time. For each step measure the drain voltage and put these values (V1 and VD) in an Excel sheet. What is ID when V1 is 5V.
  2. Replace R1 with the value in Figure 2 and repeat the procedure in Part 2,a; except that this time, just add the resulted VD in a 3rd column in your Excel sheet. Add a graph of VD of parts a and b as a function of V1 to your sheet. How are they different and why? What is ID for V1=5V?


Your report would be consisted of a Word document, an Excel sheet and all the questions asked. Also, finding the current through R1 in both cases, do you see any relation between that and the way your Excel graphs look?