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Unformatted text preview: ECE2280 Homework #8 Spring 2010 l. (a) Assume the transistors below have a finite ﬂ and an infinite Earl
equivalent circuit (hybrid7t or model T) (b) Write an expression for the input resistance Rm in the circuit shown. Your expression should include only real resistances (R1, R2, R3, R4, or a subset of these) and possibly 3, 1121 or rm, and reg or rug.
transistors have the same ﬂ.) Circle your answer. y voltage. Draw the small signal (Assume all dock (Familiar 4%?“ bag“ ' 7 52 {am am a: (paH) we! Vii. (W
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vcc 2. (a) Use the circuit shown below. Assume all transistors are active and are the same and have a finite B
and an infinite Early voltage. Draw the small signal equivalent circuit. (b) Write an expression for the input resistance Rm in the circuit shown below. Your expression should
include only real resistances (R1, R2, R3, R4, R5,R6,RG1,R62 or a subset of these) and possibly 3, re, or rn. +VCC 3 U39: ignore r0, ngEH). 7, B=100 ; (a) Solve for the DC currents: VI= 20+!) 001sinf20t)
For DC analysis, assume that the capacitors are open a. 13
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0 Io _. (b) Solve for the DC voltages: _ ': 1x
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c. VI, '=.=‘ (c) What reginn ofoperation is this transistor acting? Ad‘iVﬁ W7V3>VE (d) Sketch the tOtal instantaneous waveform observed for 14: 1f EC} 3)1,1{L{>;I
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VI = 10+0.002$in(20t)
ru1=l, 200 gm2=25mA/V, and 132:6.25uA For the following hybrid1t equivalent circuit below, ﬁnd the following values:
(a) Rm (input resistance —ignore only the input source, Vsig and include all resistors at the base)
(b) Rout (output resistance—include all resistors at the collector{no load is connected}) (c) midband gain, VV‘?
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For the following hybrid7t equivalent circuit below, find the following values:
(a) Rm (input resistance —ignore only the input source, Vsig and include all resistors at the base) (b) Rout (output resistance—include all resistors at the collector{no load is connected}) (0) midband gain, _Vo_ Vsig 2k 3kg 2kg Vo 1kQ 3k§2 am we airlltmmiilég , ﬁes ﬁbrzsrttjtlramar, ear? is; ~ @53 ,
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a”: :1» icebercexqaalmﬁlﬁafg as; 2%: armear i4: 1* g 7. For the circuit shown below, draw the AC small—signal equivalent circuit(use hybrid7t or model T). Make sure that everything is labeled in terms of the transistor number. (e. g. gml, 12,52, etc.). Include r0 for all
transistors. vsig=O.0013in(10t) AC. Assume all capacitors are shorted. THSV ESL ‘1' “xi Bil”
_. § 100m .
Vsig . ,
Q2N3904 15V j 8. Use: gm=5n1A/V, [3:50, ignore r0. What frequency pole value does C1 create? (express the answer in rad/sec.) +DV W: 9. Use: m=2mA/V, :40, i nore re. a» 533:;
g [3 g T4; " 3% gm «*5 ‘5“ What frequency pole value does C1 create? (express the answer in rad/sec.) HSV . “‘ 10. (a) IVBEI=0.7, B=100, ignore rm, vsig ={2+0.013in(wt)}Volts. Assume that the capacitor acts as an open for DC operation and short for AC operation. Does this circuit operate as a linear AC ampliﬁer? If so, what is the gain, £1.0— , of the following circuit? If not, explain why.
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w DC ‘5‘»! SQML Wt c. writ l EL Madﬁi ‘ (b) IVBEI=0.7, [3:99; ignore rm, vsig ={2+1usin(wt)}Volts. Assume that the capacitor acts as an open for DC operation and short for AC operation. Does this circuit operate as a linear AC amplifier? If so, What is the
V0 gain, V—— , of the following circuit? If not, explain why.
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VI = 20+0.001sin(20t)
For DC analysis, assume that the capacitors are open (a) Solve for the DC currents: a. 113
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(b) Solve for the DC voltages: 100 i ~>
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C. V0 .1: IE (c) What region of operation is this transistor acting? ACHV’C VA>VB>VE ((1) Sketch the total instantaneous waveform observed for Ic ifi 0] {5) [$le
the AC ampliﬁcation is Vo/V1=5V/V. I out folding 0; \oqplimmbase wavgh WWW: 4%) +Ig(%0.%) +051 —2* Islbk—Jrgg :0
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mama 0‘7 02N3904 = VE :Rout ...
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