Question

- +Voo The following common source amplifier is already biased properly. Given: gm-2 mA/V R = 20 k02 - Vour Rs 1 k NEM Cgr = 20 fF C. = 5 fF. & Rs - c a C2 = 0 Pe=20 k2 Ri= 20 k2 R, LC Cgd = 5 EF C1=00 d) Find the mid-band voltage gain vout /vi. e) What is the new mid-band voltage gain, vout /v.if capacitor C2 is removed?! 1) What is the new 3dB frequency fu if capacitor C2 is removed?

Answer 1

Dase - - - Ans: - given problem is Pute putin about Common Source amplifier. I given data for the problem is :- Jm = 2 MAIN, R1 = Rs=20kh Rza Ik-2, Cge=2017 CL56F C2= No=20k-2, R=20k-2 Cgd=5ff Ci=C4 = x Ibius Narrator Narrator = Ibias - Tout Ww c o Nuller Nuller Iso G7 - I is anything V is anything Nuppator

Depo - 1-1- & mid band Voltage hain for mid band Voltage galn we need to calculate Gm which is already given in the problem. So .. no need of de analalysis here. & we go directly for Small Signal analysis to calculate the mid band voltage gain. Smale signal analysis - what Im Vas tunt - Her resistance of the gate is very large Cle in mor order) beains of slog used as dielectric constart

Page - Puffin: & Soto No=cok Dae 1-1 - this means Early effect is present in the Scenario. * Now letus strat to calculate the midband Vottage quim. * by applying kv through outer loop that is go Im Vgs of Vot Im Vgg (vollRL)=0 g mas Vo = -9 m Vgs ( Vall Re] D D by applying KVL In Ill side Ig Rd Hun IgzoA A Vgs Vin- I g Rq - Vys=0 Vim-Ox Rs – Vgs=0 Vin - Vasco - Vgg = Vint

Puffin By putting Vgs in equation D. Vo = - Im Vin (Rellro) Van = - Jm (R21/) Mid band Voltage gain is given by TV l = 9m ( Rell ro) Materi = 2 MAX( 20K1||2K-2) ont = 2x10x 12 34 x 103_z I hope = 20x2x2 Von = 20 * @ Mid band Voltage gains after алтатит рура да сорих с 4х те са * Now we will go directly to * Small Signal analysis -

& Small signal analysis after removing Ca Puffin Removing HWWWL }R ? EOA Awit S s Im Vgs SRL pl to Im Vgg OA WWE 1 gmings - gom vys ERS

* to By applying KVL in litter loop. Vo + Im Vas Croft RL) =o Vo = - Gm Vgs ( Yol1 RL ) ) * By applying Kit at Ill side. un Ig= A 6 Vyet Vys Vin (1 + 9 m R$) It Gant gavys Vim - Ig Rs - Vgg - 9 m Vgg Rs = 0 Vin - o - Ves – Gm V9s R$' zo Vin - Vgg + gm Vgg Rs' Vin - Vgg ( 14 gm Rs1 )

Date LL Page InPuff * By putting value of legs hot eqn Vo = - Im CrollRL) x Vim (L+ Gm Rel) Vo = - In Croft RL) (ttgm Rs' 17 Midband Voltage Gain after removing by pass capacitance و ا ا Vol + Im CrollRe) It Impel + 2MAX 1032 + 2x10 3 X 3

DieLL Pasc. Puffin By removing bypass Cap: Ca mid band Voltage to gain decreas ev J by the factor of (1 + gm Rs) & Ill Impedance increases . * New 3 4K Ткала сису тн олне removing C2 the ginen circuit diagra s pomies 3R 5 Rea e Reqx Cea Cerv = C, = 5fF

Date / Pane Puffins NCC bly KCL at node + gm Vgs = IX as we have calculated that It 9 m RST Ttam ks [Vgs-ov a = IX X - R

Rew = R," _ Vall Run Q = Reax Cep E = (rollRL) X CL l = (20k/1 20k) x 5 ff = 16 KK 5fF. a = 1048571015 see E = 5xtoll see ZTY t = = 1 112 2 TX Saboll MZ SH - LETXEll- FH - - 60 Hz - 0. 3183x10 the I fr=3.183 GHZ