智慧树知到《模拟电子技术基础（西安邮电大学）》章节测试答案
智慧树知到《模拟电子技术基础（西安邮电大学）》章节测试答案
第一章单元测试
1、Which of the following is not a commonly used semiconductor material'？（）
A.carbon
B.lead
C.silicon
D.germanium
正确答案：lead
2、The characteristic of an ideal diode are those of a switch that can conduct current（）；.
A.in both directions
B.in one direction only
C.in both directions but in only one direction at a time
D.depends on the circuit it is used in
正确答案：in one direction only
3、When a diode is doped with either a pentavalent or a trivalent impurity its resistance will（）；.
A.increase
B.decrease
C.make the resistance stable against variation due to temperature
正确答案：decrease
4、The piecewise linear model， equivalent circuit of the diode consists of（）.
A.a junction capacitor， a battery， a small resistor， and the ideal diode
B.a battery， a small resistor， and the ideal diode
C.a battery and the ideal diode
D.the ideal diode
正确答案：a battery， a small resistor， and the ideal diode
5、When a p-n junction is reverse-biased， its junction resistance is（）.
A.high
B.low
C.determined by the components that are external to the device
D.constantly changing
正确答案：high
第二章单元测试
1、What is the value of the voltage dropped across forward-biased silicon diodes that are connected in parallel with each other？（）.
A.11.3 V
B.0.35 V
C.0.7 V
D.1.4 V
正确答案：0.7 V
2、The resistor voltage and resistor current in this circuit are（）.
A.10 V， 5 mA
B.11 V， 2 mA
C.11 V， 11 mA
D.2 V， 11 mA
正确答案：11 V， 11 mA
3、Which of the following circuits is used to eliminate a portion of a signal？（）.
A.Clipper
B.Damper
C.Voltage multiplier
D.Voltage divider
正确答案：Clipper
4、The circuit shown here is a（）.
A.series clipper
B.parallel clipper
C.series clamper
D.shunt clamper
正确答案：parallel clipper
5、The Zener diode must be operated such that（）.
A.
B.
；is less than the specified；
C.the applied voltage is greater than；
D.All of these
正确答案：All of these
第三章单元测试
1、In the active region， the base-emitter junction（）.
A.and the base-collector junctions are both forward-biased
B.and the base-collector junctions are both reverse-biased
C.is forward-biased while the base-collector junction is reversed-biased
D.is reverse-biased while the base-collector junction is forward-biased
正确答案：is forward-biased while the base-collector junction is reversed-biased
2、A BJT has measured dc current values of
= 0.1 mA and
= 8.0 mA.When IB is varied by 100 μA， IC changes by 10 mA.What is the value of the βac for this device？（）.
A.80
B.10
C.100
D.800
正确答案：100
3、When a BJT is operating in the active region， the voltage drop from the base to the emitter
is approximately equal to the（）。
A.base bias voltage
B.base current times the base resistor
C.diode drop（about 0.7 V）
D.emitter voltage
正确答案：diode drop（about 0.7 V）
4、BJTs are commonly used as（）.
A.the primary components in amplifiers
B.series damper circuits
C.the primary components in rectifiers
正确答案：the primary components in amplifiers
5、The condition where increase in bias current will not cause further increases in collector current is called（）.
A.cutoff
B.saturation
C.active operation
正确答案：saturation
第四章单元测试
1、When a BJT is biased in the cutoff region the collector-to-emitter voltage is typically equal to（）.
A.the emitter voltage
B.0.03 V
C.the collector current times the collector resistor
D.the collector supply voltage
正确答案：the collector supply voltage
2、Calculate the collector-emitter voltage for this emitter-stabilized circuit.（）；
A.4.32 V
B.10.68 V
C.0.1335 V
D.14.24 V
正确答案：4.32 V
3、The difference between the resulting equations for a network in which an npn transistor has been replaced by a pnp transistor is（）.
A.the values of the resistors
B.the value of β
C.the sign associates with the particular quantities
正确答案：the sign associates with the particular quantities
4、The term quiescent means（）.
A.midpoint-biased
B.at rest
C.active
D.inactive
正确答案：inactive
5、Voltage-divider bias stability is（）.
A.dependent on alpha
B.dependent of beta
C.dependent on the collector resistor
D.independent of beta
正确答案：independent of beta
第五章单元测试
1、Given this configuration， determine the input impedance if VS = 40 mV， Rsense = 0.5 kΩ， and the input current is 20 μA.（）
A.1.5 MΩ
B.5.822 MΩ
C.1，500 Ω
D.582 kΩ
正确答案：1，500 Ω
2、The
transistor model replaces the（）；with the junction diode'；s ac resistance.。
A.collector-base junction
B.collector-emitter junction
C.emitter（）base junction
正确答案：emitter（）base junction
3、Calculate the voltage gain for this circuit.（）
A.-137.25
B.-8.4
C.-7.91
D.-16.34
正确答案：-137.25
4、A transistor amplifier has an input signal applied to its emitter terminal and an output signal taken from its collector terminal.The amplifier is a（n）（）.
A.common-emitter amplifier
B.common-base amplifier
C.common-collector amplifier
D.emitter follower
正确答案：common-base amplifier
5、The voltage gain of a very well-designed common collector amplifier configuration， using a pnp transistor， is（）.
A.about -0.9
B.about 0.9
C.in the range 0.95 to 0.99
D.in the range -0.95 to -0.99
正确答案：in the range 0.95 to 0.99
第六章单元测试
1、Shockley'；s equation defines the（）；of the FET and are unaffected by the network in which the device is employeD.
A.
；characteristics
B.drain characteristics
C.input/output characteristics
D.transfer characteristics
正确答案：transfer characteristics
2、For an n-channel depletion MOSFET，
= 8 mA and
= -6 V.If
= 0.8 V， what is the value of the drain current，
？（）
A.8 mA
B.10.25 μA
C.10.28 mA
D.6 mA
正确答案：10.28 mA
3、The region of the JFET drain curve that lies between pinch-off and breakdown is called（）.。
A.the constant-voltage region
B.the ohmic region
C.the saturation region
正确答案：the saturation region
4、In the family of FETs， you can expect to find（）.。
A.an；n-channel type
B.a；p-channel type
C.unipolar structure
正确答案：an；n-channel type；a；p-channel type；unipolar structure
5、FETs usually（）.
A.are less sensitive to temperature change than BJTs
B.have a higher input impudence than BJTs
C.are smaller in construction than BJTs
正确答案：are less sensitive to temperature change than BJTs；have a higher input impudence than BJTs；
are smaller in construction than BJTs
第七章单元测试
1、This graphical solution represents（）.
A.fixed bias for an；n-channel JFET
B.voltage-divider bias for an；n-channel JFET
C.self bias for an；n-channel JFET
正确答案：self bias for an；n-channel JFET
2、Generally， it is good design practice for linear amplifiers to have operating points that close to（）.
A.are close to saturation level
B.the cut-off region
C.the midpoint of the load line
正确答案：the midpoint of the load line
3、Which of the following biasing circuits can be used with E-MOSFETs？（）
A.self bias
B.zero bias
C.drain-feedback bias
D.current-source bias
正确答案：drain-feedback bias
4、The primary difference between JFETs and depletion-type MOSFETs is（）.。
A.JFETs can have positive values of
；and levels of drain current that exceed
B.depletion-type MOSFETs can have positive values of
；and levels of
；that exceed
C.depletion-type MOSFETs can have only positive of
正确答案：depletion-type MOSFETs can have positive values of
；and levels of
；that exceed
5、A JFET can be biased in several different ways.The common method（s） of biasing an n-channel JFET is（are）（）.
A.self-bias configuration
B.voltage-divider bias configuration
C.fixed-bias configuration
正确答案：self-bias configuration；voltage-divider bias configuration；fixed-bias configuration
第八章单元测试
1、The FET version of the BJT'；s common-emitter configuration is the（）；circuit.
A.common-source
B.common-gate
C.common-drain
D.common-current
正确答案：common-source
2、Calculate the input impedance for this FET amplifier.（）
A.
B.
C.
D.
；= would depend on the drain current
正确答案：
3、Design this circuit for a voltage gain of 10.You have to calculate the value of resistor
and
.It is desired that the transistor operate with a relatively high value of
.For this device， a high value of
is defined as
.（）
A.
B.
C.
D.
正确答案：
4、The（）；amplifier has high input impedance， low output impedance， and low voltage gain.。
A.common-gate
B.common-drain
C.common-source
正确答案：common-drain
5、The（）；FET amplifier has low input impedance， high output impedance， and high voltage gain.。
A.common-gate
B.common-drain
C.common-source
正确答案：common-gate
第九章单元测试
1、Calculate the low frequency break point due to the capacitor；
for this BJT amplifier.（）
A.
B.
C.
D.
正确答案：
2、If several identical stages of amplifiers， each having the exact same upper and lower cutoff frequencies， are connected in cascade， then the bandwidth of the resulting amplifier will（）.
A.increase
B.remain unchanged
C.decrease
D.be equal to the sum of all the individual bandwidths
正确答案：decrease
3、A 3-dB drop in β occurs at（）.
A.
B.
C.
D.
正确答案：
4、Negative dB values represent（）.
A.power gain
B.power losses
C.power values that do not change
正确答案：power losses
5、An amplifier has a midband power gain of 24，500.What is the value of the power gain in dB for the circuit？（）
A.87.78 dB
B.43.9 dB
C.4.39 dB
正确答案：43.9 dB
第十章单元测试
1、Under difference-mode operation， the difference-mode voltage gain for this circuit is（）.
A.0.0397
B.80
C.40
D.0.08
正确答案：40
2、The operational amplifier will only slightly amplify signals（）.
A.when the supply voltages are more then ±25 V
B.when the supply voltages are less then ±5 V
C.that are common on both the inputs
D.that are different on both the inputs
正确答案：that are common on both the inputs
3、The inverting and noninverting inputs to an op-amp are used to drive a（n）（）；amplifier.
A.inverting
B.noninverting
C.differential
D.open-loop
正确答案：differential
4、When a given op-amp has a common-mode input of 10 V， the output of the device is 10 V.；When the device has a differential input of 2 mV， the output of the device is 10 V.What is the CMPR of the device？（）
A.5 ：1
B.5000 ：1
C.1000 ：1
D.5，000，000 ：1
正确答案：5000 ：1
5、The bandwidth of an amplifier is（）.
A.the range of frequencies over which gain remains relatively constant
B.the range of frequencies between the lower and upper 3 dB frequencies
C.the range of frequencies found using；
第十一章单元测试
1、If the input voltage is 0.25 V and the output is -2.5 V， the value of
；must be（）.
A.40.0 kΩ
B.20.0 kΩ
C.16.0 kΩ
D.5.0 kΩ
正确答案：20.0 kΩ
2、The output voltage， VO， is given by（）.
A.
B.
C.
正确答案：
3、A summing integrator is an op-amp integrator that has（）.
A.multiple feedback capacitors
B.multiple input resistors
C.multiple input resistors and feedback capacitors
正确答案：multiple input resistors and feedback capacitors
4、A second order low-pass filter has a high-end roll-off of（）.。
A.60 dB/octave
B.40 dB/decade
C.20 dB/octave
D.6 dB/decade
正确答案：40 dB/decade
5、An active filter that provides a constant output for input signals above
is called an ideal（）.
A.low-pass filter
B.high-pass filter
C.bandpass filter
正确答案：high-pass filter
第十二章单元测试
1、A class B amplifier（not push-pull）（）.
A.conducts through 360° of the input waveform
B.conducts through 180° of the input waveform
C.conducts between 180° and 360° degrees of the input waveform， depending on the amount of dc bias
D.conducts through less than 180° of the input waveform
正确答案：conducts through 180° of the input waveform
2、Crossover distortion in class B amplifiers is prevented by（）.。
A.biasing the transistors deeply into cutoff
B.biasing the transistors slightly above cutoff
C.using complementary-symmetry transistors
D.increasing the load resistance
正确答案：biasing the transistors slightly above cutoff
3、The maximum theoretical efficiency of an RC-coupled class A amplifier is（）.
A.25%
B.50%
C.78.5%
D.99%
正确答案：25%
4、Power amplifiers are typically used to drive low impedance loads.（）。
A.正确
B.错误
正确答案：正确
5、The power that an amplifier delivers to a load is equal to the difference between the power that the circuit draws from the power supply and the power that the circuit dissipates.（）。
A.正确
B.错误
正确答案：正确
第十三章单元测试
1、The feedback circuit connection shown here is（）.
A.voltage series feedback
B.voltage shunt feedback
C.current series feedback
D.current shunt feedback
正确答案：voltage series feedback
2、Calculate the voltage gain for voltage series feedback when the amplifier gain is A = -2000 and F = -1/50.（）
A.-2000
B.-1/50
C.50
D.-48.78
正确答案：-48.78
3、Calculate the input impedance for voltage series feedback when the amplifier has
= 10 kΩ， amplifier gain is A = -2000， and F=
.（）
A.input impedance with feedback 10 kΩ
B.input impedance with feedback 410 kΩ
C.input impedance with feedback 244 Ω
D.input impedance with feedback 50 Ω
正确答案：input impedance with feedback 410 kΩ
4、The output impedance of current-shunt feedback amplifier（）；the output impedance of its op-amp.
A.is increased when compared to
B.is decreased when compared to
C.is reduced by half when compared to
D.has no effect on
正确答案：is increased when compared to
5、An amplifier has a gain-bandwidth product of 200 MHz.A feedback network is added that has a feedback factor（1 + βA） of 18.88.What is the gain-bandwidth product for the circuit with the added feedback network？（）
A.10.59 MHz
B.18.88 MHz
C.200 MHz
正确答案：200 MHz
第一章单元测试
1、Which of the following is not a commonly used semiconductor material'？（）
A.carbon
B.lead
C.silicon
D.germanium
正确答案：lead
2、The characteristic of an ideal diode are those of a switch that can conduct current（）；.
A.in both directions
B.in one direction only
C.in both directions but in only one direction at a time
D.depends on the circuit it is used in
正确答案：in one direction only
3、When a diode is doped with either a pentavalent or a trivalent impurity its resistance will（）；.
A.increase
B.decrease
C.make the resistance stable against variation due to temperature
正确答案：decrease
4、The piecewise linear model， equivalent circuit of the diode consists of（）.
A.a junction capacitor， a battery， a small resistor， and the ideal diode
B.a battery， a small resistor， and the ideal diode
C.a battery and the ideal diode
D.the ideal diode
正确答案：a battery， a small resistor， and the ideal diode
5、When a p-n junction is reverse-biased， its junction resistance is（）.
A.high
B.low
C.determined by the components that are external to the device
D.constantly changing
正确答案：high
第二章单元测试
1、What is the value of the voltage dropped across forward-biased silicon diodes that are connected in parallel with each other？（）.
A.11.3 V
B.0.35 V
C.0.7 V
D.1.4 V
正确答案：0.7 V
2、The resistor voltage and resistor current in this circuit are（）.
A.10 V， 5 mA
B.11 V， 2 mA
C.11 V， 11 mA
D.2 V， 11 mA
正确答案：11 V， 11 mA
3、Which of the following circuits is used to eliminate a portion of a signal？（）.
A.Clipper
B.Damper
C.Voltage multiplier
D.Voltage divider
正确答案：Clipper
4、The circuit shown here is a（）.
A.series clipper
B.parallel clipper
C.series clamper
D.shunt clamper
正确答案：parallel clipper
5、The Zener diode must be operated such that（）.
A.
B.
；is less than the specified；
C.the applied voltage is greater than；
D.All of these
正确答案：All of these
第三章单元测试
1、In the active region， the base-emitter junction（）.
A.and the base-collector junctions are both forward-biased
B.and the base-collector junctions are both reverse-biased
C.is forward-biased while the base-collector junction is reversed-biased
D.is reverse-biased while the base-collector junction is forward-biased
正确答案：is forward-biased while the base-collector junction is reversed-biased
2、A BJT has measured dc current values of
= 0.1 mA and
= 8.0 mA.When IB is varied by 100 μA， IC changes by 10 mA.What is the value of the βac for this device？（）.
A.80
B.10
C.100
D.800
正确答案：100
3、When a BJT is operating in the active region， the voltage drop from the base to the emitter
is approximately equal to the（）。
A.base bias voltage
B.base current times the base resistor
C.diode drop（about 0.7 V）
D.emitter voltage
正确答案：diode drop（about 0.7 V）
4、BJTs are commonly used as（）.
A.the primary components in amplifiers
B.series damper circuits
C.the primary components in rectifiers
正确答案：the primary components in amplifiers
5、The condition where increase in bias current will not cause further increases in collector current is called（）.
A.cutoff
B.saturation
C.active operation
正确答案：saturation
第四章单元测试
1、When a BJT is biased in the cutoff region the collector-to-emitter voltage is typically equal to（）.
A.the emitter voltage
B.0.03 V
C.the collector current times the collector resistor
D.the collector supply voltage
正确答案：the collector supply voltage
2、Calculate the collector-emitter voltage for this emitter-stabilized circuit.（）；
A.4.32 V
B.10.68 V
C.0.1335 V
D.14.24 V
正确答案：4.32 V
3、The difference between the resulting equations for a network in which an npn transistor has been replaced by a pnp transistor is（）.
A.the values of the resistors
B.the value of β
C.the sign associates with the particular quantities
正确答案：the sign associates with the particular quantities
4、The term quiescent means（）.
A.midpoint-biased
B.at rest
C.active
D.inactive
正确答案：inactive
5、Voltage-divider bias stability is（）.
A.dependent on alpha
B.dependent of beta
C.dependent on the collector resistor
D.independent of beta
正确答案：independent of beta
第五章单元测试
1、Given this configuration， determine the input impedance if VS = 40 mV， Rsense = 0.5 kΩ， and the input current is 20 μA.（）
A.1.5 MΩ
B.5.822 MΩ
C.1，500 Ω
D.582 kΩ
正确答案：1，500 Ω
2、The
transistor model replaces the（）；with the junction diode'；s ac resistance.。
A.collector-base junction
B.collector-emitter junction
C.emitter（）base junction
正确答案：emitter（）base junction
3、Calculate the voltage gain for this circuit.（）
A.-137.25
B.-8.4
C.-7.91
D.-16.34
正确答案：-137.25
4、A transistor amplifier has an input signal applied to its emitter terminal and an output signal taken from its collector terminal.The amplifier is a（n）（）.
A.common-emitter amplifier
B.common-base amplifier
C.common-collector amplifier
D.emitter follower
正确答案：common-base amplifier
5、The voltage gain of a very well-designed common collector amplifier configuration， using a pnp transistor， is（）.
A.about -0.9
B.about 0.9
C.in the range 0.95 to 0.99
D.in the range -0.95 to -0.99
正确答案：in the range 0.95 to 0.99
第六章单元测试
1、Shockley'；s equation defines the（）；of the FET and are unaffected by the network in which the device is employeD.
A.
；characteristics
B.drain characteristics
C.input/output characteristics
D.transfer characteristics
正确答案：transfer characteristics
2、For an n-channel depletion MOSFET，
= 8 mA and
= -6 V.If
= 0.8 V， what is the value of the drain current，
？（）
A.8 mA
B.10.25 μA
C.10.28 mA
D.6 mA
正确答案：10.28 mA
3、The region of the JFET drain curve that lies between pinch-off and breakdown is called（）.。
A.the constant-voltage region
B.the ohmic region
C.the saturation region
正确答案：the saturation region
4、In the family of FETs， you can expect to find（）.。
A.an；n-channel type
B.a；p-channel type
C.unipolar structure
正确答案：an；n-channel type；a；p-channel type；unipolar structure
5、FETs usually（）.
A.are less sensitive to temperature change than BJTs
B.have a higher input impudence than BJTs
C.are smaller in construction than BJTs
正确答案：are less sensitive to temperature change than BJTs；have a higher input impudence than BJTs；
are smaller in construction than BJTs
第七章单元测试
1、This graphical solution represents（）.
A.fixed bias for an；n-channel JFET
B.voltage-divider bias for an；n-channel JFET
C.self bias for an；n-channel JFET
正确答案：self bias for an；n-channel JFET
2、Generally， it is good design practice for linear amplifiers to have operating points that close to（）.
A.are close to saturation level
B.the cut-off region
C.the midpoint of the load line
正确答案：the midpoint of the load line
3、Which of the following biasing circuits can be used with E-MOSFETs？（）
A.self bias
B.zero bias
C.drain-feedback bias
D.current-source bias
正确答案：drain-feedback bias
4、The primary difference between JFETs and depletion-type MOSFETs is（）.。
A.JFETs can have positive values of
；and levels of drain current that exceed
B.depletion-type MOSFETs can have positive values of
；and levels of
；that exceed
C.depletion-type MOSFETs can have only positive of
正确答案：depletion-type MOSFETs can have positive values of
；and levels of
；that exceed
5、A JFET can be biased in several different ways.The common method（s） of biasing an n-channel JFET is（are）（）.
A.self-bias configuration
B.voltage-divider bias configuration
C.fixed-bias configuration
正确答案：self-bias configuration；voltage-divider bias configuration；fixed-bias configuration
第八章单元测试
1、The FET version of the BJT'；s common-emitter configuration is the（）；circuit.
A.common-source
B.common-gate
C.common-drain
D.common-current
正确答案：common-source
2、Calculate the input impedance for this FET amplifier.（）
A.
B.
C.
D.
；= would depend on the drain current
正确答案：
3、Design this circuit for a voltage gain of 10.You have to calculate the value of resistor
and
.It is desired that the transistor operate with a relatively high value of
.For this device， a high value of
is defined as
.（）
A.
B.
C.
D.
正确答案：
4、The（）；amplifier has high input impedance， low output impedance， and low voltage gain.。
A.common-gate
B.common-drain
C.common-source
正确答案：common-drain
5、The（）；FET amplifier has low input impedance， high output impedance， and high voltage gain.。
A.common-gate
B.common-drain
C.common-source
正确答案：common-gate
第九章单元测试
1、Calculate the low frequency break point due to the capacitor；
for this BJT amplifier.（）
A.
B.
C.
D.
正确答案：
2、If several identical stages of amplifiers， each having the exact same upper and lower cutoff frequencies， are connected in cascade， then the bandwidth of the resulting amplifier will（）.
A.increase
B.remain unchanged
C.decrease
D.be equal to the sum of all the individual bandwidths
正确答案：decrease
3、A 3-dB drop in β occurs at（）.
A.
B.
C.
D.
正确答案：
4、Negative dB values represent（）.
A.power gain
B.power losses
C.power values that do not change
正确答案：power losses
5、An amplifier has a midband power gain of 24，500.What is the value of the power gain in dB for the circuit？（）
A.87.78 dB
B.43.9 dB
C.4.39 dB
正确答案：43.9 dB
第十章单元测试
1、Under difference-mode operation， the difference-mode voltage gain for this circuit is（）.
A.0.0397
B.80
C.40
D.0.08
正确答案：40
2、The operational amplifier will only slightly amplify signals（）.
A.when the supply voltages are more then ±25 V
B.when the supply voltages are less then ±5 V
C.that are common on both the inputs
D.that are different on both the inputs
正确答案：that are common on both the inputs
3、The inverting and noninverting inputs to an op-amp are used to drive a（n）（）；amplifier.
A.inverting
B.noninverting
C.differential
D.open-loop
正确答案：differential
4、When a given op-amp has a common-mode input of 10 V， the output of the device is 10 V.；When the device has a differential input of 2 mV， the output of the device is 10 V.What is the CMPR of the device？（）
A.5 ：1
B.5000 ：1
C.1000 ：1
D.5，000，000 ：1
正确答案：5000 ：1
5、The bandwidth of an amplifier is（）.
A.the range of frequencies over which gain remains relatively constant
B.the range of frequencies between the lower and upper 3 dB frequencies
C.the range of frequencies found using；
第十一章单元测试
1、If the input voltage is 0.25 V and the output is -2.5 V， the value of
；must be（）.
A.40.0 kΩ
B.20.0 kΩ
C.16.0 kΩ
D.5.0 kΩ
正确答案：20.0 kΩ
2、The output voltage， VO， is given by（）.
A.
B.
C.
正确答案：
3、A summing integrator is an op-amp integrator that has（）.
A.multiple feedback capacitors
B.multiple input resistors
C.multiple input resistors and feedback capacitors
正确答案：multiple input resistors and feedback capacitors
4、A second order low-pass filter has a high-end roll-off of（）.。
A.60 dB/octave
B.40 dB/decade
C.20 dB/octave
D.6 dB/decade
正确答案：40 dB/decade
5、An active filter that provides a constant output for input signals above
is called an ideal（）.
A.low-pass filter
B.high-pass filter
C.bandpass filter
正确答案：high-pass filter
第十二章单元测试
1、A class B amplifier（not push-pull）（）.
A.conducts through 360° of the input waveform
B.conducts through 180° of the input waveform
C.conducts between 180° and 360° degrees of the input waveform， depending on the amount of dc bias
D.conducts through less than 180° of the input waveform
正确答案：conducts through 180° of the input waveform
2、Crossover distortion in class B amplifiers is prevented by（）.。
A.biasing the transistors deeply into cutoff
B.biasing the transistors slightly above cutoff
C.using complementary-symmetry transistors
D.increasing the load resistance
正确答案：biasing the transistors slightly above cutoff
3、The maximum theoretical efficiency of an RC-coupled class A amplifier is（）.
A.25%
B.50%
C.78.5%
D.99%
正确答案：25%
4、Power amplifiers are typically used to drive low impedance loads.（）。
A.正确
B.错误
正确答案：正确
5、The power that an amplifier delivers to a load is equal to the difference between the power that the circuit draws from the power supply and the power that the circuit dissipates.（）。
A.正确
B.错误
正确答案：正确
第十三章单元测试
1、The feedback circuit connection shown here is（）.
A.voltage series feedback
B.voltage shunt feedback
C.current series feedback
D.current shunt feedback
正确答案：voltage series feedback
2、Calculate the voltage gain for voltage series feedback when the amplifier gain is A = -2000 and F = -1/50.（）
A.-2000
B.-1/50
C.50
D.-48.78
正确答案：-48.78
3、Calculate the input impedance for voltage series feedback when the amplifier has
= 10 kΩ， amplifier gain is A = -2000， and F=
.（）
A.input impedance with feedback 10 kΩ
B.input impedance with feedback 410 kΩ
C.input impedance with feedback 244 Ω
D.input impedance with feedback 50 Ω
正确答案：input impedance with feedback 410 kΩ
4、The output impedance of current-shunt feedback amplifier（）；the output impedance of its op-amp.
A.is increased when compared to
B.is decreased when compared to
C.is reduced by half when compared to
D.has no effect on
正确答案：is increased when compared to
5、An amplifier has a gain-bandwidth product of 200 MHz.A feedback network is added that has a feedback factor（1 + βA） of 18.88.What is the gain-bandwidth product for the circuit with the added feedback network？（）
A.10.59 MHz
B.18.88 MHz
C.200 MHz
正确答案：200 MHz