Traditionally operating a MOS transistor in strong inversion region is the analog designers choice in their design space[1, 2]. Transconductance of a MOS transistor is . We have three degrees of freedom.
EKV Model is a physical model, was proposed by Enz, Krummenacher, and Vittoz from EPFL.
The channel current in weak inversion region is given by
n is subthreshold slope factor (~ 1.5 in 180nm CMOS tech).
Trans-conductance in weak inversion region is
gm/id methodology is used to size transistors, particularly in short channel devices or deep sub-micron technologies.
The following data is generated over a reasonable range of and channel lengths
Generate data for the following over a reasonable range of gm/ID and channel lengths
- Transit frequency (fT)
- Intrinsic gain (gm/gds)
- Current density (ID/W)
These parameters are (to first order) independent of transistor width, which enables “normalized design”.
In a MOS transistor as increases, generation efficiency decreases. is maximum in weak inversion, and almost constant over a large range in this region.