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(ELEC101)exam_pastd.pdf
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(b)
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Text Box: (a) Show that the resistivity of intrinsic (pure) silicon (Si) is 2278 ..-m. (b) A silicon is doped with Indium (gr
Text Box: Hence dope Si with 5x1021 Indium/m3 .
Text Box: The resistivity of intrinsic Si
Text Box: Density of electrons is given by
Text Box: p-type Si
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2
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Text Box: Find VO / VS in terms of R, C and jw. If C = 1.YF , R1 = 1k.., R2 = 10k.., find the complex transfer function G
Text Box: Circuit is a high pass filter
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(a)
Text Box: . In the ideal op amp circuit, the diode equation is . whe
Text Box: If V2 = - 0.62V D is a ON diode
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VO= Vi + Vc = -10 C10= -20 V
Vc = -10V
3V
3V
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(b)
Text Box: (b) In the ideal diode circuit, find Vc and sketch Vo(t). Label clearly VO(t) . Assume the diode is ideal. (12)
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(c)
Text Box: (c) In the diode circuit, sketch and label clearly VO(t) . D2 is an ideal diode and D1 is an offset diode with
Text Box: VO
VZK = 7V
rZ = 5.
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e
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1. EBJunction is a forward bias (on) diodeand BC is reverse bias (off) diode
2. E is very heavily doped(N +for NPN). E has many electrons,
3. B is very thin. So most electronsinjected from E (to B) are attracted to C and
Text Box: Draw the cross sectional structure of a NPN BJT transistor operated in the amplifier mode, describe the movement of
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VO(t)
RC
RB
Vi= 0.74V
Text Box: Given the BJT circuit below and the IC -VCE curve of the BJT. The Q point is chosen as IC = 18mA and VCE = 5V. (a)
Text Box: vi(t)
VCE2 = 6V
Draw load line,
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(a)
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IB = 0.16mA
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(b)
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(a)
Text Box: (a) Find IC / IB . Given RE = 1k.. and Vi = 7V. Show clearly your reasons. For the BJT, given VBE(ON) = 0.
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RC = 1k.
RB = 1k.
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(b)
Text Box: . Draw the small signal (AC) equivalent circuit of the BJT amplifier and find the voltage gain AV ( = Vout / Vin
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Text Box: (a) Use Boolean algebra to show that (9)
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9
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4.87510.100.1112
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P
Q
P
R
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Text Box: (c) Express decimal number 4.87510 into binary number. (6)
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ID
IS
source usually shorted to body
Metallic film
IG= 0
ID= IS
An NMOSFET consists of a metal gateinsulated from a p-type semiconductorsubstrate (or body) by an insulating layer of silicon dioxide. On either side of the gate there are n type regions forming the drain and source.