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comparing CS and Cascode frequency response

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!

Reply to
Matteo
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Re-read the text book?

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
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Reply to
Jim Thompson

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..)

Reply to
Matteo

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