The relationship of the BW of a source follower with its bias current

[alexang1983]

Dear All,
I am looking for a relationship (equation) that links the BW of a source follower with its bias current.
Can you help me please?
Thanks

 

[lsimeon]

source follower

from the very basic relationship of time and current; I=q/t , where I is the current q is the charge and t is the time it takes an electron to pass a certain place in a circuit... we know that the BW is a function of frequency which is the inverse of time so I conclude that Current is directly proportional to BW... for the equation, try to read the book of Boylestad...

 

[salerno]

source follower

In brief, the dominant pole, therefore the bandwidth, is given by

fp=1/(2pi)*gm/(CL+Cgs),
where gm is the transconductance
Cgs is the gate-source capacitance
CL is the load capacitance

Since gm is given by
gm=2*sqrt(k*W/L*Id)

we have got the relationship between BW and current.