MOS transistor in subthreshold

[lhlbluesky]

for MOS transistor in subthreshold, how to calculate its Gm, early voltage?

and what is the relationship of gain and early voltage?

and someone says, MOS transistor in subthreshold can have the largest gain, but

why? is that because working with small operating current?

pls help me. thanks all.

 

[erikl]

For Gm & gain ≈ Gm/Id s. E. Vittoz' paper on weak inversion below, p. 10

For Early voltage s. Berkeley's BSIM manual, CHAP2N.pdf (below), p. 24 ff.

 

[lhlbluesky]

thanks erikl