Background Theory > Spice Simulation > Devices

In SPICE (Simulation Program with Integrated Circuit Emphasis), MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are modeled to simulate the behavior of these semiconductor devices in electronic circuits. MOSFETs are a type of field-effect transistor that uses the electric field generated by a gate terminal to control the flow of current between the source and drain terminals..

SPICE provides various MOSFET models to accurately represent their behavior under different operating conditions. MOSFET models in SPICE include idealized models as well as more advanced models that consider non-ideal characteristics, temperature effects, and other relevant parameters.

Here are some key MOSFET models in SPICE:

Ideal MOSFET Model

The ideal MOSFET model is a simplified representation of a MOSFET that captures its basic behavior. It assumes that the MOSFET operates in its linear (ohmic) region when biased and provides a constant current when on.

Non-Ideal MOSFET Models

More advanced MOSFET models in SPICE consider non-ideal characteristics such as channel length modulation, mobility variation, gate-source capacitance, temperature effects, and more.

Some of the advanced MOSFET models include:

•MOSFET Level 1 Model: This model includes parameters such as trans-conductance, threshold voltage, and channel length modulation to provide a more accurate representation of MOSFET behavior.

•MOSFET Level 3 Model: This model is more comprehensive and includes additional parameters to account for mobility variation, gate-source capacitance, and temperature effects.

•BSIM (Berkeley Short-Channel IGFET Model): This is a family of advanced MOSFET models developed at UC Berkeley. BSIM models provide even greater accuracy and include additional features for modeling sub-micron MOSFET behavior.

MOSFET models in SPICE are used to analyze MOSFET behavior in various circuit applications, such as amplifiers, switches, analog circuits, digital circuits, and more. Depending on the accuracy required for your simulation and the complexity of the circuit, you can choose the appropriate MOSFET model that suits your design needs. Keep in mind that while ideal MOSFET models are simple to use, they may not capture all the nuances of real-world MOSFET behavior.