hi all, I calculated the frequency response of the CS and Cascode amplifiers using the time constants method. Here they are:
CS
f = ( 2*PI*( Rs*Cgs + Rs*Cgs*(1+Av) + Rd*(Cdb+Cl)) )^-1
Cascode
f = ( 2*PI*(Rs*Cgs1 + Cds1*2*Rs + Rd*(Cgd2+Cdb2*Cl) + 1/gm2*(Cdb1+Cgs2) )^-1
where:
Rs = resistance of the imput signal Rd = resistance under Vdd Cl = load capacity
I calculated f using
Rs = 50ohm Rd = 600ohm W = 592 micron
and I obtained
CS => f = 1.98EE+08 Cascode => 2.08EE+08
and I think that's a really little difference! where did I make the mistake?
thank you very much!