Simple Nmos/Pmos Pspice model file

Nikki,

Transistor level models are fitted to several sets of data taken on various test structures. The equation set of the model (MOS1, MOS3, BSIM, BSIM3v3, etc.) determines the methodology for how to fit the parameters to the data as each set of data gives insight into how the transistor performs as well as to how the transistor was made. Fitting a MOSFET (NMOS or PMOS) normally requires a specific program that takes in the data and varies multiple parameters in the model equation set and then calculates an error value. This process is iterative and is only complete when the targeted error is reduced to the value that is acceptable for the fit.

Since a 5V transistor and a 10V transistor will have different physical construction, the data and the model fitting would be different. There is not a single parameter that you can adjust to make a 5V transistor a 10V transistor model. The transistor model takes in the Length, Width, VDS, VGS, VBS and uses these values to calculate the performance values of the transistor.

A 5V transistor model may work at 10V, however, it will not represent a 10V transistor behavior. It will represent a set of model equations used with parameters that are valid at 5V, but give some kind of solution at 10V. However, an experienced modeling engineer can take a 5V model for a transistor and convert it to a 10V transistor model provided that they know the differences in construction, the model equations being used, an idea of what the tagreted performance parameters are for the 10V device, and the time the run several simulations on the modified mode to verify that it functions as expected.

Britt