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Unformatted text preview: Name Soauflobg§ Rensselaer Polytechnic Institute
Department of Electrical, Computer and Systems Engineering ECSEZOSO Spring 2001 Quiz II Print your name on every page and show all work to ensure partial credit. Problem 1 (30 points)
Problem 2 (25 points)
Problem 3 (20 points) Problem 4 (25 points) Total Name SoLuTloNS Problem 1:' Consider the BJT ampliﬁer circuit shown below. Assume that all the capacitors
are very large, B = 150 and VA = 300 V. W _.  1 .—
VCE’IAV ‘9 C '3— b) Determine the values of R1 and R2 which produce a bias point of IC = 2 mA. Design for
bias stability and ven'fy that the BJT is in the active mode. .1— IS‘I' :
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B gi+‘t}(;o> Name q c) Find the values of the small signal parameters r“, gm and r0 for IC = 2 mA. ,. ‘ u ,
p: I": 65" W = magma
H b 3.", 9441A gm: ‘3" C ﬁnd/A = SOmA/V F 1A, 32.59.: Noun.
,0' :9. :MH ,1 d) Draw the small signal model for the complete ampliﬁer. Assume operation in the midfre
quency region and indicate the values of all components on the circuit. You do not need to
analyze the circuit. loo
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WW /. 2 7:142. Name Problem 2:' The BJT in the circuit below has [3 = 150. The JFET has IDSS = 10 mA and Vp = 2 V.
Iov a) Solve for the voltages V1 through V5. Show all your work and validate any assumptions 591 :1» about the mode of operation for the transistors.
ea Assm £37m «m =.> V5194
to’okis +.‘7 t °I.lK(tSDIB= to V1: 10014.13 = 'GSl V = VI , é o
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.3 ~' 9.5K ' LLEK 9.3K i‘LBL Name 35’”*< lés>+ ”V05 *9) = 9M1“ — 4351mm; VdS 2.: V6: +10%“ Ho , 3‘.231V¢$ 5.9/63" + 10.8) Vcs + g ., O 41/P
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I'D: 2,;3;(/.03')= 2&qu
VT: — . " — g, 7‘73V > V63“.
V95: Vq'Vs‘  $.39 ( MM Name Problem 3:. The MOSFET in the circuit drawn below has k’(W/L) = 0.5 mA/Vz and vT = 2 v.
w all(L Rs 10 a) Select R1 and R2 to make VG = 10 V and R1R2 = 3 M9 E R 12:. .L...L=5rl_n_ , . ((4):;0 R+rt> Rl+lz3
[2* —_ {425 q) .4952» :BHJL =9—
Rﬁl‘} , 10 b) Assume VG = 10 V. Select Rs to get a bias point ofID = 3 mA. Name Problem 4: ' The MOSFET in the circuit below has k’(W/L) = 0.25 mA/V2 and VT = 3 V and is biased with
ID = 1 mA. Also, R1R2 = 5 M!) aox/ 3 a) Determine the value of gm. 8 b) Draw the small signal model for the complete circuit, showing the values of all parameters.
Assume that the capacitors are very large and that we are concerned with midfrequency oper
ation. Name 9 c) Using the small signal model drawn in (b), ﬁnd the value of the voltage gain vo/vi and the
input resistance R (as shown on the diagram). Show all your work in deriving the results. M15 * mi; V0 : “ 3m N1$(7K.\Hok) “‘ 3m N4. (NUHOK) M“: 'Mgs 4 ' W — N ‘ N“ + ‘ TE 3 45 :7: 3mm
‘4 $K*‘1M a, d) Find the input loading factor, LF, and use this value to ﬁnd the voltage gain vo/vs. 255
$K+€%$ L's: : 0’”; . N :
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