2. * Vout = Vds1
Av=Vov2/Vov2 ??
I think this.
Voh = Vdd-Vth2
max where Voh=Vdd-Vds2 and Rds2=Vds2/Id2
Vol = RdsOn1 * Ith2
min (Ith2 = current at Vgs2=Vth2=Vds2)
Thus Aol = gain is related Voh
max - Vol
min or Rds2/Rds1
Rds is related to beta and Vgs
In the saturation region, Ids = beta * (Vgs - Vt)^2 / 2.
Test
If |Vth| = 1.5 for both thus Voh
max = 3.5V
beta1 = 20m like CD4xxx series
beta2 = 80m like 74ALCxx series so what is Ids
max?
Vdd =5V Vgs bias = 1.75V what is Vol
min
What is Aol max?
Razavi says.. Aol= |Vgs2-Vth2)| / (Vgs1-Vth1)
Using my example, Vgs2= |5-1.75-1.5|=3.25 and Vgs2-Vth2=1.75
Vgs1=1.75, so Vgs1-Vth1= 0.25
Aol =1.75/0.25 = 7
with 500 mVpp in and 3Vpp out from 0.5 to 3.5V out.
Avg=2.0V out, 1.75V in
hmm my simulation
http://tinyurl.com/yp732lj4
gives me Aol=6
...close but no cigar
Anyone else?