Question

Voc Ri Rc C2 + RS G Q2N3904 RL Vout 2 R2 RE CE Rin Rout Cu B 1x B C o + V be : Cr 8m'be E VCC R R2 Rc RE RS RL С. Cz CE 12 V 8.2 kg 3.9 ko 6.3 k2 3.3 kΩ 3 ko 3.9 ko 10 uF 1uF 100 u Assume the 2N3904 has a 8 =100, Veron} = 0.7V, VA= 100V, C=100, C=13.9pF and Ce=8pF. Use the emission coefficient as n = 1 and V1=25mv. 1. Analyze the DC circuit to determine the Q-point(ic, Vce) and leg. 2. Using the hybrid-r small signal model and assuming all capacitors as short circuits to AC voltages, find the input and output impedances, Rn and Rout, and midband voltage gain Av mid = Vaud/Vin (do not neglect and ). In what case (Tea<< ?) the base resistance r, has a negligible effect on Av mid and Rn 3. Find the short circuit time constant of all the external capacitors by the drawing the circuits, used to find the equivalent resistance at the terminals of the each capacitor. Find the low cut-off frequency of the amplifier using short circuit time constant method. 4. Find the open circuit time constant of all internal capacitance by the drawing the circuits, used to find the equivalent resistance at the terminals the each capacitance. Find the high cut-off frequency of the amplifier using open circuit time constant method. 5. Find the bandwidth of the amplifier.

Answer 1

R ..+12 kr.<<< Sna नि Prabou Then Rx can be Ka Ica Poak

Given COMMON Emitter amplifier Rq = 3.9ku Re = 6.3k1 RE = 3.3 kr R = 8.2Kn Vcc = 120 Rg = 3 kr RL = 3.9kr G = 10uF C2 =luf CE = 100MG 8x=1000 VA-100V P-100 Belon-0177 V = 25mu Su=8pf C = 1309 pf CE amplifier Dc- equivalent of Vcc=lav Re B PEITIB Pc = BIB Pf= ((HB) IB wwwww t NCE IB RBB UBE

Input equation th-IB ROB UBE-PEPE=0 th Vee Re Rit Rg 19% 3.9x103 (8.943.97X102 1943.9 1901 tha 3.867 volts PBB? R, Rq RutPię 3,9x82x106 121 X 103 2.649 kr RBB = 2.643 kr I B RBB +(1+B) I ₂ RE Uth-OBE 3.867 - 0of IB 3o167 Ree+(1+3) RE (2.643+(101) 3.3]/IĆ IB 3.167 335.943 X1013 -6 9.4272x10 °Amps IB = 91272 M

-6 Pc = BIB 100४ १.५१११५० 1c 0.१५3.+2 mA - 0.95NA ला Ic Nb.१५3 mA FE~ 0.958 mA → output equation Nec-Ichle - UcE - PERE 20 Yec Į RC FIERE =VCE ७८E, \2-(७-१u3x 6.3) - (0-१5२४3-3) 12- 3.1५२१-5.qull UCE 2.91-70015 Ic XIA 0.943x107 25-13 न In- 0.0342 m

OK Na IB 95x103 9.1919x10-6 8 = 2.652 ku 100+ 9.917 do= VATUCE 0.943x103 8o = 109.138 kel Ica 0.943mA VCE Q=2017 volts IBQ = 9.1972MA → small signal Ac- equivalent of CE amplifier B Rs Ib 8x Im Ube R88 be on R Yout سع t

yout - -9 m be Collell be = Ug [Roll & tox) +(10 : Boll Rll A = 109.138xall 6.3 kell 3.9kus = 109.138k1|| 2.4088 KM roll Relle = 2.3567 kn 구 Roll Loxton) 2bu3 Kell (2652+100) 2.buskall 2.752k1 Roll Contoy) 163489 kr 3 Roll (oxton) 163u89x10 =0.31005 Rg+ (Pg 11 (8,4A) 3x10247.34824103

AVE Gle -gamite till. 18.] [Roll(1,023 yoe [RestCel12,477) AN= -9m [doll Pelle] [Rellot Prs + C Rell Cox+37] AJP -0.03749x 7.3567x103 x 0.31005 Av=-27.562 % → Rona Rell (oxtrA Ro=fall Re 109.138 kal) 63 kr Ro = 5.956 ka Ren= 103482 Kel

short circuit time constants equivalent circuit wodot low frequency Rg ci www 73 mo be + be to “อีก man Vg BB R RE Time constant We det i с Req= Ryt [Roll (oxton)] + [1•3489x103) Oxton Ross 22 • 3x10 Reg 3.3u8qku C = Loup

" = C, Rea 10X10 6X U. 3uF 9x1073 = U6 348 2x10-2 = 0.0u3u89 secsl 1=20.048 > We bot la [ce- - Soc and G-5.c) Cq Reai all be the RE -5.956 kat 3.9k1 to 9.856 kn .no Ta = Reqca - 9o85% x103x 10-6 ܘܐܢ = 0.009856 sec

We lot a Im "be 1687 BI 16 + Yobe $0,10) (Roll Ree) I b (1+B) n NA 11 PBB) I + C&gton] I = Vx Uy = Ib [Pill PB8+ (85707) Ko Pull Post laston Req= TRE 1 (148) 26 (1+B) Rieq Rell [951188 + (ostro] - 1-р

31083/19.643210)+(9-452x4] 3.3x103) Redio 101 Beste 3.313 || [.u051 + U051 + (9-752J 4103 lol Rég 3.3x103 || [4.1571x103 10) Req = 3630103|| 41:159 hora Reg= 48.65 19h — ſz. Reg. ce : 40.6519 x 100x10 5 = 30.6519xio“ sec > T = Ti + Te + Tz 40 3482x102t +9.856x10*7 40.6919810-4 434.822104 + 98.568104 + 40.6519x1024

د ( 10 ) 32 3\0 sec \ .. A 25 51.039 vio 104 \ماه ۱۹ -- 48x5 1.039 95 = . 1435 A3 حد

High Model frequency cu Roig Сое B с. с with to ex-Req. Rspg [fr,1974 2:31 IRA Resig T = CARsig 12.652x0 - 1-4051x10 +100 1 - 9600171x13.9 Pf (409614100)11 2652 = 150501 11 2652 y = 13346.34 p sec - 960.17lu with au (Ca is 0.c) Is is applied across Cbc

Roig "L Vg be R ! almy € Vg Rear Is Ube Is Psig U = Ug tube Ig - 9 mbete Ri Pg - Im be + Vg to be RU Pure that is a sig in aan te P= PBCCM

RBC = Rogg - 9600171 [1+0.03749x 2.3567x103J+R! +9356.7 Rsiq=960-171 (1488-890] . 86314-307 7935657 Req=68671.00 +1 & Realu = 88671.807x8 Pf 70936800563 Pfee { = Tth [109368.0 8.0563+ 133 ub371] P sec ľ - 722714.4273 x1012 12 10 for at 2T T 25x129714.4273

fH O. 22091 MHZ Bandwidth a fx-fu 0.22091x10-201125 H3 Bandwidth = 990215.5289 H3