220-A3.1

Activity: MOSFET Characteristic Curves

• Instructions: This activity is structured as a tutorial with an activity at the end. Should you have any questions, clarifications, or issues, please contact your instructor as soon as possible.
• At the end of this activity, the student should be able to:

1. Generate the characteristic curves of NMOS and PMOS transistors.

MOS Transfer Characteristics

Figure 1: A circuit to obtain the V-I characteristics of an NMOS transistor.

The transfer characteristics of an NMOS transistor is the relationship between the gate-source voltage, which serves as the "input" port of a common-source amplifier, and the "output" drain current. To simulate the transfer characteristic of our 45nm NMOS PTM model, we can use this SPICE file and this Python script.

Activity 1: MOS Operating Regions

Use the given SPICE file and Python scripts to plot out the NMOS transfer characteristics, as shown in Figs. 2 and 3. Graphically, identify the following regions:

• The quadratic or square-law region
• The velocity saturation region
• The subthreshold or weak inversion region
• The moderate inversion region.

Figure 2: The NMOS transfer characteristics.

Figure 3: The NMOS transfer characteristics on a log scale.

MOS Output Characteristics

Figure 4: The NMOS output characteristics.