Chapter 20

Introducing MOSFETs

A MOSFET is defined by the MOSFET model and element parameters, and two submodels selected by the CAPOP and ACM model parameters. The CAPOP model parameter specifies the model for the MOSFET gate capacitances. The ACM (Area Calculation Method) parameter selects the type of diode model to be used for the MOSFET bulk diodes. Each of these submodels has associated parameters that define the characteristics of the gate capacitances and bulk diodes.

MOSFET models are either p-channel or n-channel models; they are classified according to level such as LEVEL 1 or LEVEL 50.

This chapter covers the design model and simulation aspects of MOSFET models, parameters of each model level, and associated equations. MOSFET diode and MOSFET capacitor model parameters and equations are also described. For information about individual models and their parameters, see Selecting MOSFET Models: LEVEL 1-40 and Selecting MOSFET Models: LEVEL 47-62.

This chapter describes:

• Understanding MOSFET Models
• Selecting Models
• Using the General MOSFET Model Statement
• Using Nonplanar and Planar Technologies
• Using MOSFET Equivalent Circuits
• Using a MOSFET Diode Model
• Using MOS Diode Equations
• Using Common Threshold Voltage Equations
• Performing MOSFET Impact Ionization
• Using MOS Gate Capacitance Models
• Using Noise Models
• Using Temperature Parameters and Equations