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Unformatted text preview: Name SULuﬂ 0N5 Rensselaer Polytechnic Institute
Department of Electrical, Computer and Systems Engineering ECSEZOSO Spring 2003 Quiz 2 Print your name on every page and show all work to ensure partial credit. Problem 1 (20 points)
Problem 2 (30 points)
Problem 3 (20 points) Problem 4 (30 points) Total Name Song mus Problem 1: Consider the JFET circuit shown below. Assume that the device parameters are I =10mAandV =4V.
Dss P ‘HS'V Q‘ '1 E Herc.— a) The output characteristics for the JFET are shown below. Draw a DC load line on this plot
and indicate the bias point where VDS = 7.5 V. Be sure to indicate the ID for the bias point. i1) (IDA) 10 Name SK, 5441'! 0M3 b) Determine the values of R1 and R2 which produce a bias point of VDS = 7.5 V. Make RIHRZ
= 1 MO __  lass _
)0 >_ _
(.y)l(v&$+q) = '2 5 ‘3 “4/6.; 5 “34/ s (/3 = (:SmAMAM = {v
R; 23%,: Sa=3\/ : K,m,(’s> FEB; 09— mm “ 543%}  Name out/Tl AM“ Problem 2: I Consider the B] T ampliﬁer in the circuit below. Assume that the BJT has VBE = 0.7 V in the
active mode and B = 100 and VA = 50 V. Assume that the capacitors are very large. V33 Awarov \OKIL. a) Determine the value of VBB that produces IC = 1 mA. Verify that the BJT is in the active
mode with IC = 1 mA. .. l  1.3.
L£=lmP\ ‘6 ﬁlm“ ) .EB Hm = IO/AA l“ E:(Stcx1mm= 5V Vg=S‘l'.'—l v ~91
25:”: 'OV‘M “‘9 VBB‘ 477V
V66: 30— rostrum  Shown: sv >..t yum b) Determine the small signal parameters for the BJT and draw the complete small signal model
for the ampliﬁer, indicating the value for all components. Assume VT = 25 mV. t ngv _
_ _———'— : ‘5 (W' g lG’uept J 1w“: J”; a .MA ‘(0 mA/V
VT” .3va r0: Ki 2:9“ 5’0!ch
Io Imp! Name SOLUWOM‘S c) Calculate the small signal gain, vo/vi, when RL = 00 . Note that vi is the small signal voltage
at the base of the transistor. You must derive your result from the small signal model above. N0 = qmwm (\m'llgom (Vbe ‘ “’6
z.) Mo = *.O‘~( (8.33% M d) Calculate the input resistance, R, as indicated on the schematic. You must derive your result from the small signal model above. RC = look ll 9.5L UI Name Saga/z] 9N: e) Calculate the output resistance, R0, as indicated on the schematic diagram. You must derive
your result from the small signal model above. Ra: toKuS‘csK a 233:“; 0 Use your answers from (c), (d) and (e) to compute the input and output loading factors and
the overall gain, vo/vs, when RL = 10 k9 Name Sam/n (5 M3 Problem 3: The MOSFET in the circuit drawn below has k’(W/L) = 2 mA/V2 and VT = 2 V. The BJT has
VBE = 0.7 V in the active mode, [3 = 50 and VT = 25 mV. +OV JED: 3.34 \mD. = #05“? m“ ‘ Zlk’(w/z.)(vg$._%_)a lvkgvﬁ ‘ 3:22 1;.) V“: ans) tw <VT
V6: Vow Vs ‘ 5“HMB = cmw ISQK _
V .: ’ __ _
6 Mamﬁ‘ (mv) = 4,.v3v an) R1 83. 5k b) Find the range of R2 values for which Q] is in the current saturation mode and V0 = 3_V. Vb: > VangVT r ATE—D... =,13\/
v5: 3.1Va VB: \0— 1:935 V95 '1 AIG" R;( LOS‘QMR") ’37? > .‘73 => Problem 4: The MOSFET in the circuit below has k’(W/L) = 4 mA/Vz, VT = 2 V and VA = 50 V Assume that the capacitors are very large. + tov a) Find the small signal parameters for the MOSFET and draw the small signal model labelin
all components. j g :5 A v ’
~1:3, m gm— “at; (w/QIX3 '’ 6.5 mMV
r0: .5”... C mg : IDKJZ... b) Derive the voltage gain, vo/vi, from the small signal model. “" V4 3CD No 4.
gm lNL'
Ickluok SM Name SULUS 19193 c) Derive the input resistance, Ri, from the small signal model. . , N4; . a
PC ' 4"
c a ’ [Vt—No w M" + (3/.SN") : 33.5”
‘ S'M " sh 5“ ‘ d) Derive the output resistance, R0, from the small signal model. R0: i ...
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 Spring '08
 MonaHella
 Rensselaer Polytechnic Institute, Smallsignal model, small signal model

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