comparing CS and Cascode frequency response

Discussion in 'Electronic Design' started by Matteo, May 2, 2007.

1. MatteoGuest

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

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!

2. Jim ThompsonGuest

...Jim Thompson

3. MatteoGuest

Jim Thompson ha scritto:
Uhmmm ..What do you mean for? Are you going to tell me that it could NOT
be a mistake...?
I posted my work about Cascode configuration in sci.electronics.basics
group (maybe it's better if you answer there, sorry for the mess..)