CMOS Design > MOS Modeling Précedant suivant

What is a MOS model?

Modeling the MOS device consists in writing a set of equations that link voltages and currents, in order to simulate and predict the behavior of the single device, and consequently the behavior of a complete circuit. For MOS devices, one of the key objective of the model is to evaluate the current Ids which flows between the drain and the source, depending on the supply voltages Vd, Vg, Vs and Vb.

The equations represent the variation of the current Ids versus voltages in two different ways, as illustrated in the figure. The graphs are usually called "Ids/Vds", "Ids/Vgs". For simplicity, we consider that the voltage Vs is grounded. This assumption has no consequence on the results.

A model is made of :
  • some equations describing IDS (VDS) and IDS (VGS)
  • some parameters linked with the technology and given by the fonder




CMOS Design > MOS Modeling > What is a MOS model? Précedant suivant