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Question
Design an emitter follower as shown in
Fig.1. Assume VCC=15V, VBE=0.7 V,
VCE(sat)=0.5V,IR=10mA,andRL=1kΩ.
Assume
identical
transistors
of
βF=hfe=100. Find the voltage, current,
and power rating of the transistors and
also determine the critical value of load
resistance to avoid clipping, and
calculate the peak-to-peak output
voltage swing Vpp if RL=2kΩ.
The parameters of the emitter follower
in Fig. 2 are VCC=12 V, R1=2.5kΩ, and
RL=750Ω.The transistors are identical,
and their parameters are VBE=0.7 V,
VCE (sat) = 0.5 V, and βF=hfe=100.
Determine
(a) the peak voltage and current of
transistor Q1 and
(b) the average output power PL,
(c) the power efficiency,
(d) the value of RL for maximum
efficiency, and
(e) the corresponding value of efficiency max.
Design a class-A amplifier, as shown in Fig.3, for high efficiency.
The audio output power is 48W. The available supply voltage is
Marks
ISE
SEE
12M
12M
8M
BTL
Taken
From
Text
Book:
T1:11,
pp:798
Text
Book:
T1:11,
pp:798799
Text
Book:
T1:11,
pp:799
12V. Assume transistors of
βF=hfe=100. Find the voltage,
current, and power rating of the
transistors.
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The parameters of the class-A
amplifier in Fig.4 are VCC=15V,
R1=15kΩ, and RL=1kΩ. The
transistors are identical, and their
parameters are VBE=0.7V, VCE (sat)
= 0.5V, and βF=hfe=100.
Determine
(a) the peak voltage and current
of transistor Q1,
(b) the average output power PL,
and
(c) the efficiency η.
Design a complementary class-B push-pull amplifier, to supply an
output power of PL=16W at a load resistance of RL=4Ω.Assume a
DC supply voltage of VCC=15V and transistors of βF=hfe=100 and
VBE=0.7V.
Find the voltage, current, and power rating of the transistors.
12M
12M
Text
Book:
T1:11,
pp:799
Text
Book:
T1:11,
pp:799
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Calculate the power efficiency η and power dissipation PD of each
transistor in the complementary class-B push-pull output stage in
Fig.6 if VCC=15V and RL=10Ω. The parameters of the transistors
are βF=hfe=150, VCE(sat)=0.2V, and VBE=0.7V.
Design a transformer-coupled
load class A amplifier, as shown
in Fig.7, to have high efficiency
and to supply an output power
of PL=32W at a load resistance
of RL=8Ω. Assume a DC supply
voltage of VCC=15 V.
Find the voltage, current, and
power rating of the transistors
and the transformer turns
ratio. Assume βF=hfe=100 and
VCE(sat)=0.5 V.
The
parameters
of
the
transformer-coupled
load
class-A amplifier in Fig.8 are
VCC=15V and RL=16Ω. The
transistor
parameters
are
VBE=0.7V, VCE(sat)=0.5 V, and
hfe=100. The transformer turns
ratio is 2:1. Determine
(a) the peak voltage and
current of transistor Q1
(b) the average output power
PL, and (c) the efficiency η.
The power dissipation of a transistor is specified as PD(max)=250
W at TC0=25°C. The transistor is mounted on a heat sink. The
12M
12M
12M
6M
Text
Book:
T1:11,
pp:799
Text
Book:
T1:11,
pp:799
Text
Book:
T1:11,
pp:799
Text
Book:
4
2
10
thermal resistances are θJC=0.7°C⁄W, θCS=0.2°C⁄W, and
θSA=0.8°C⁄W.If TJ(max)=200°C and TA=45°C, calculate the
maximum permissible power dissipation of the transistor.
The power dissipation of a transistor is specified as PD(max)=290
W at TC0=25°C. The transistor is mounted on a heat sink. The
thermal resistances of the transistor are θJC=0.6°C⁄W and
θCS=0.2°C⁄W.If TJ(max)=200°C, TC=150°C, and TA=45°C,
calculate the required thermal resistance of the heat sink θSA.
T1:11,
pp:799
6M
Text
Book:
T1:11,
pp:799