智慧树知到《模拟电子技术基础（西安邮电大学版）》章节测试答案

智慧树知到《模拟电子技术基础（西安邮电大学版）》章节测试答案
第一章
1、Which of the following is not a monly used semiconductor material’? （ ）
A:carbon
B:lead
C:silicon
D:germanium
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
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
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
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 ponents that are external to the device
D:constantly changing
答案: high
第二章
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:35 V
C:7 V
D:4 V
答案: 7 V
2、The resistor voltage and resistor current in this circuit are （ ）.image.png
A:10 V, 5 mA
B:11 V, 2 mA
C:11 V, 11 mA
D:2 V, 11 mA
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
答案: Clipper
4、The circuit shown here is a （ ）. image.png
A:series clipper
B:parallel clipper
C:series clamper
D:shunt clamper
答案: parallel clipper
5、The Zener diode must be operated such that （ ）.
A:image.png
B:image.png is less than the specified image.png
C:the applied voltage is greater than image.png
D:All of these
答案: All of these
第三章
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
答案:  C
2、A BJT has measured dc current values of image.png = 0.1 mA and image.png= 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
答案: C
3、When a BJT is operating in the active region, the voltage drop from the base to the emitter image.png 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
答案: C
4、BJTs are monly used as （ ）.
A:the primary ponents in amplifiers
B:series damper circuits
C:the primary ponents in rectifiers
答案: A
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
答案: B
第四章
1、When a BJT is biased in the cutoff region the collector-to-emitter voltage is typically equal to （ ）.
A:the emitter voltage
B:03 V
C:the collector current times the collector resistor
D:the collector supply voltage
答案: D
2、Calculate the collector-emitter voltage for this emitter-stabilized circuit.（ ） image.png
A:32 V
B:10.68 V
C:1335 V
D:14.24 V
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
答案: C
4、The term quiescent means （ ）.
A:midpoint-biased
B:at rest
C:active
D:inactive
答案: D
5、Voltage-divider bias stability is （ ）.
A:dependent on alpha
B:dependent of beta
C:dependent on the collector resistor
D:independent of beta
答案: D
第五章
1、Given this configuration, determine the input impedance if VS = 40 mV, Rsense = 0.5 kΩ, and the input current is 20 μA.（ ）image.png
A:5 MΩ
B:822 MΩ
C:1,500 Ω
D:582 kΩ
答案: C
2、The image.png transistor model replaces the （ ） with the junction diode’s ac resistance.
A:collector-base junction
B:collector-emitter junction
C:emitter—base junction
答案: C
3、Calculate the voltage gain for this circuit. （ ）image.png
A:-137.25
B:-8.4
C: -7.91
D:-16.34
答案: A
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:mon-emitter amplifier
B:mon-base amplifier
C:mon-collector amplifier
D:emitter follower
答案: B
5、The voltage gain of a very well-designed mon 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
答案: C
第六章
1、Shockley’s equation defines the （ ） of the FET and are unaffected by the network in which the device is employed.
A:image.png characteristics
B:drain characteristics
C:input/output characteristics
D:transfer characteristics
答案: D
2、For an n-channel depletion MOSFET, image.png= 8 mA and image.png = -6 V. If image.png= 0.8 V, what is the value of the drain current, image.png? （ ）
A:8 mA
B:10.25 μA
C:10.28 mA
D:6 mA
答案: C
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
答案: C
4、In the family of FETs, you can expect to find （ ）.
A:an n-channel type
B:a p-channel type
C:unipolar structure
答案: ABC
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
答案: ABC
第七章
1、This graphical solution represents （ ）.image.png
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
答案: C
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
答案: C
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
答案: C
4、The primary difference between JFETs and depletion-type MOSFETs is （ ）.
A:JFETs can have positive values of image.png and levels of drain current that exceed image.png
B:depletion-type MOSFETs can have positive values of image.png and levels of image.png that exceed image.png
C:depletion-type MOSFETs can have only positive of image.png
D:JFETs can have only positive values of image.png
答案:  B
5、A JFET can be biased in several different ways. The mon method(s) of biasing an n-channel JFET is(are) （ ）.
A:self-bias configuration
B:voltage-divider bias configuration
C:fixed-bias configuration
答案: ABC
第八章
1、The FET version of the BJT’s mon-emitter configuration is the （ ） circuit.
A:mon-source
B:mon-gate
C:mon-drain
D:mon-current
答案: A
2、Calculate the input impedance for this FET amplifier. （ ）image.png
A:image.png
B:image.png
C:image.png
D:image.png = would depend on the drain current image.png
答案:
3、Design this circuit for a voltage gain of 10. You have to calculate the value of resistor image.png and image.png. It is desired that the transistor operate with a relatively high value of image.png. For this device, a high value of image.png is defined as image.png. （ ）image.png
A:image.png
B:image.png
C:image.png
D:image.png
答案:
4、The （ ） amplifier has high input impedance, low output impedance, and low voltage gain.
A:mon-gateB:mon-drain
C:mon-source
答案: B
5、The （ ） FET amplifier has low input impedance, high output impedance, and high voltage gain.
A:mon-gate
B:mon-drain
C:mon-source
答案: A
第九章
1、Calculate the low frequency break point due to the capacitor image.png for this BJT amplifier. （ ）image.png
A:image.png
B:image.png
C:image.png
D:image.png
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
答案: C
3、A 3-dB drop in β occurs at （ ）.
A:image.png
B:image.png
C:image.png
D:image.png
答案:
4、Negative dB values represent （ ）.
A:power gain
B:power losses
C:power values that do not change
答案: B
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:39 dB
答案: B
第十章
1、Under difference-mode operation, the difference-mode voltage gain for this circuit is （ ）.image.png
A:0397
B:80
C:40
D:08
答案: C
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 mon on both the inputs
D:that are different on both the inputs
答案:C
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
答案: C
4、When a given op-amp has a mon-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
答案: B
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 image.png
答案: ABC
第十一章
1、 If the input voltage is 0.25 V and the output is -2.5 V, the value ofimage.png must be （ ）.image.png
A:40.0 kΩ
B:20.0 kΩ
C:16.0 kΩ
D:0 kΩ
答案: B
2、The output voltage, VO, is given by （ ）.image.png
A:image.png
B:image.png
C:image.png
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
答案: C
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
答案: B
5、An active filter that provides a constant output for input signals above image.png is called an ideal （ ）.
A:low-pass filter
B:high-pass filter
C:bandpass filter
答案: B
第十二章
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
答案: B
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 plementary-symmetry transistors
D:increasing the load resistance
答案: B
3、The maximum theoretical efficiency of an RC-coupled class A amplifier is （ ）.
A:25%
B:50%
C:78.5%
D:99%
答案: A
4、Power amplifiers are typically used to drive low impedance loads.（ ）
A:对
B:错
答案: A
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:对
B:错
答案: A
第十三章
1、The feedback circuit connection shown here is （ ）.image.png
A:voltage series feedback
B:voltage shunt feedback
C:current series feedback
D:current shunt feedback
答案: B
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
答案: D
3、Calculate the input impedance for voltage series feedback when the amplifier has image.png = 10 kΩ, amplifier gain is A = -2000, and F= image.png. （ ）
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
答案: B
4、The output impedance of current-shunt feedback amplifier （ ） the output impedance of its op-amp.
A:is increased when pared to
B:is decreased when pared to
C:is reduced by half when pared to
D:has no effect on
答案: A
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
答案: C