2021知到答案 模拟电子技术基础（西安邮电大学） 最新智慧树满分章节测试答案

第三章 单元测试

1、单选题：
In the active region, the base-emitter junction  （    ）.
选项：
A:and the base-collector junctions are both forward-biased
B:is reverse-biased while the base-collector junction is forward-biased
C:is forward-biased while the base-collector junction is reversed-biased
D:and the base-collector junctions are both reverse-biased
答案: 【is forward-biased while the base-collector junction is reversed-biased】

2、单选题：
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?（    ）.
选项：
A:80
B:10
C:800
D:100
答案: 【100】

3、单选题：
When a BJT is operating in the active region, the voltage drop from the base to the emitter  is approximately equal to the （    ）。
选项：
A:emitter voltage
B:base current times the base resistor
C:base bias voltage
D:diode drop (about 0.7 V)
答案: 【diode drop (about 0.7 V)  】

4、单选题：
BJTs are commonly used as （    ）.
选项：
A:the primary components in rectifiers
B:series damper circuits
C:the primary components in amplifiers
答案: 【the primary components in amplifiers】

5、单选题：
The condition where increase in bias current will not cause further increases in collector current is called （    ）.
选项：
A:saturation
B:active operation
C:cutoff
答案: 【saturation】

第四章 单元测试

1、单选题：
When a BJT is biased in the cutoff region the collector-to-emitter voltage is typically equal to （    ）.

选项：
A:the collector supply voltage
B:the emitter voltage
C:the collector current times the collector resistor
D:0.03 V
答案: 【the collector supply voltage 】

2、单选题：
Calculate the collector-emitter voltage for this emitter-stabilized circuit.（    ） 
选项：
A:14.24 V
B:4.32 V
C:10.68 V
D:0.1335 V
答案: 【4.32 V】

3、单选题：
The difference between the resulting equations for a network in which an npn transistor has been replaced by a pnp transistor is （    ）.
选项：
A:the value of β
B:the values of the resistors
C:the sign associates with the particular quantities
答案: 【the sign associates with the particular quantities】

4、单选题：
The term quiescent means （    ）.
选项：
A:inactive
B:at rest
C:active
D:midpoint-biased
答案: 【inactive】

5、单选题：
Voltage-divider bias stability is （    ）.
选项：
A:dependent on alpha
B:dependent of beta
C:independent of beta
D:dependent on the collector resistor
答案: 【independent of beta】

第五章 单元测试

1、单选题：
Given this configuration, determine the input impedance if VS = 40 mV, Rsense = 0.5 kΩ, and the input current is 20 μA.（    ）
选项：
A:582 kΩ
B:1.5 MΩ
C:5.822 MΩ
D:1,500 Ω
答案: 【1,500 Ω】

2、单选题：
The  transistor model replaces the （    ） with the junction diode’s ac resistance.
选项：
A:collector-emitter junction
B:collector-base junction
C:emitter—base junction
答案: 【emitter—base junction  】

3、单选题：
Calculate the voltage gain for this circuit. （   ）
选项：
A:-8.4
B:-16.34
C: -7.91
D:-137.25
答案: 【-137.25】

4、单选题：
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) （    ）.
选项：
A:emitter follower
B:common-emitter amplifier
C:common-base amplifier
D:common-collector amplifier
答案: 【common-base amplifier】

5、单选题：
The voltage gain of a very well-designed common collector amplifier configuration, using a pnp transistor, is （    ）.
选项：
A:in the range -0.95 to -0.99
B:about -0.9
C:in the range 0.95 to 0.99
D:about 0.9
答案: 【in the range 0.95 to 0.99】

第六章 单元测试

1、单选题：
Shockley’s equation defines the （    ） of the FET and are unaffected by the network in which the device is employed.
选项：
A:input/output characteristics
B:drain characteristics
C:transfer characteristics
D: characteristics
答案: 【transfer characteristics】

2、单选题：
For an n-channel depletion MOSFET, = 8 mA and  = -6 V. If = 0.8 V, what is the value of the drain current, ?  （    ）
选项：
A:8 mA
B:6 mA
C:10.28 mA
D:10.25 μA
答案: 【10.28 mA】

3、单选题：
The region of the JFET drain curve that lies between pinch-off and breakdown is called （    ）.
选项：
A:the saturation region
B:the constant-voltage region
C:the ohmic region
答案: 【the saturation region】

4、多选题：
In the family of FETs, you can expect to find （     ）.
选项：
A:an n-channel type
B:a p-channel type
C:unipolar structure
答案: 【an n-channel type;a p-channel type;unipolar structure】

5、多选题：
FETs usually （    ）.
选项：
A:are less sensitive to temperature change than BJTs
B:

are smaller in construction than BJTs

C:have a higher input impudence than BJTs
答案: 【are less sensitive to temperature change than BJTs;

are smaller in construction than BJTs

;have a higher input impudence than BJTs】

第七章 单元测试

1、单选题：
This graphical solution represents （    ）.
选项：
A:self bias for an n-channel JFET
B:fixed bias for an n-channel JFET
C:voltage-divider bias for an n-channel JFET
答案: 【self bias for an n-channel JFET】

2、单选题：
Generally, it is good design practice for linear amplifiers to have operating points that close to （    ）.
选项：
A:are close to saturation level
B:the midpoint of the load line
C:the cut-off region
答案: 【the midpoint of the load line】

3、单选题：
Which of the following biasing circuits can be used with E-MOSFETs?   （    ）
选项：
A:current-source bias
B:drain-feedback bias
C:zero bias
D:self bias
答案: 【drain-feedback bias】

4、单选题：
The primary difference between JFETs and depletion-type MOSFETs is （    ）.
选项：
A:depletion-type MOSFETs can have only positive of 
B:JFETs can have only positive values of 
C:depletion-type MOSFETs can have positive values of  and levels of  that exceed 
D:JFETs can have positive values of  and levels of drain current that exceed 
答案: 【depletion-type MOSFETs can have positive values of  and levels of  that exceed 】

5、多选题：
A JFET can be biased in several different ways. The common method(s) of biasing an n-channel JFET is(are) （    ）.
选项：
A:fixed-bias configuration
B:voltage-divider bias configuration
C:self-bias configuration
答案: 【fixed-bias configuration;voltage-divider bias configuration;self-bias configuration】

第八章 单元测试

1、单选题：
The FET version of the BJT’s common-emitter configuration is the （    ） circuit.
选项：
A:common-source
B:common-current
C:common-gate
D:common-drain
答案: 【common-source】

2、单选题：
Calculate the input impedance for this FET amplifier.  （    ）
选项：
A: = would depend on the drain current 
B:
C:
D:
答案: 【】

3、单选题：
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 . （    ）
选项：
A:
B:
C:
D:
答案: 【】

4、单选题：
The （    ） amplifier has high input impedance, low output impedance, and low voltage gain.
选项：
A:common-source
B:common-drain
C:common-gate
答案: 【common-drain】

5、单选题：
The （    ） FET amplifier has low input impedance, high output impedance, and high voltage gain.
选项：
A:common-source
B:common-drain
C:common-gate
答案: 【common-gate】

第九章 单元测试

1、单选题：
Calculate the low frequency break point due to the capacitor  for this BJT amplifier. （   ）
选项：
A:
B:
C:
D:
答案: 【】

2、单选题：
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 （    ）.
选项：
A:remain unchanged
B:decrease
C:be equal to the sum of all the individual bandwidths
D:increase
答案: 【decrease】

3、单选题：
A 3-dB drop in β occurs at （    ）.
选项：
A:
B:
C:
D:
答案: 【】

4、单选题：
Negative dB values represent （    ）.
选项：
A:power values that do not change
B:power losses
C:power gain
答案: 【power losses】

5、单选题：
An amplifier has a midband power gain of 24,500. What is the value of the power gain in dB for the circuit? （     ）
选项：
A:43.9 dB
B:4.39 dB
C:87.78 dB
答案: 【43.9 dB】

第十章 单元测试

1、单选题：
Under difference-mode operation, the difference-mode voltage gain for this circuit is （     ）.

选项：
A:0.0397
B:80
C:40
D:0.08
答案: 【40】

2、单选题：
The operational amplifier will only slightly amplify signals （    ）.
选项：
A:when the supply voltages are more then ±25 V
B:that are different on both the inputs
C:that are common on both the inputs
D:when the supply voltages are less then ±5 V
答案: 【that are common on both the inputs】

3、单选题：
The inverting and noninverting inputs to an op-amp are used to drive a(n) （    ） amplifier.
选项：
A:noninverting
B:inverting
C:open-loop
D:differential
答案: 【differential】

4、单选题：
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? （    ）
选项：
A:5000 : 1
B:5 : 1
C:5,000,000 : 1
D:1000 : 1
答案: 【5000 : 1】

5、多选题：

The bandwidth of an amplifier is （     ）.
选项：
A: the range of frequencies found using 
B:the range of frequencies between the lower and upper 3 dB frequencies
C:the range of frequencies over which gain remains relatively constant
答案: 【 the range of frequencies found using ;the range of frequencies between the lower and upper 3 dB frequencies;the range of frequencies over which gain remains relatively constant  】

第十一章 单元测试

1、单选题：
If the input voltage is 0.25 V and the output is -2.5 V, the value of must be （    ）.
选项：
A:20.0 kΩ
B:16.0 kΩ
C:5.0 kΩ
D:40.0 kΩ
答案: 【20.0 kΩ】

2、单选题：
The output voltage, VO, is given by （    ）.
选项：
A:
B:
C:
答案: 【】

3、单选题：
A summing integrator is an op-amp integrator that has （    ）.
选项：
A:multiple feedback capacitors
B:multiple input resistors and feedback capacitors
C:multiple input resistors
答案: 【multiple input resistors and feedback capacitors】

4、单选题：
A second order low-pass filter has a high-end roll-off of （    ）.
选项：
A:40 dB/decade
B:20 dB/octave
C:60 dB/octave
D:6 dB/decade
答案: 【40 dB/decade】

5、单选题：
An active filter that provides a constant output for input signals above  is called an ideal （    ）.
选项：
A:bandpass filter
B:high-pass filter
C:low-pass filter
答案: 【high-pass filter】

第十二章 单元测试

1、单选题：
A class B amplifier (not push-pull) （     ）.
选项：
A:conducts through less than 180° 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 360° of the input waveform
答案: 【conducts through 180° of the input waveform】

2、单选题：
Crossover distortion in class B amplifiers is prevented by （    ）.
选项：
A:biasing the transistors deeply into cutoff
B:biasing the transistors slightly above cutoff
C:using complementary-symmetry transistors
D:increasing the load resistance
答案: 【biasing the transistors slightly above cutoff】

3、单选题：
The maximum theoretical efficiency of an RC-coupled class A amplifier is （    ）.
选项：
A:25%
B:99%
C:78.5%
D:50%
答案: 【25%】

4、判断题：
Power amplifiers are typically used to drive low impedance loads.（     ）
选项：
A:错
B:对
答案: 【对】

5、判断题：
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.（     ）
选项：
A:错
B:对
答案: 【对】

第十三章 单元测试

1、单选题：
The feedback circuit connection shown here is （      ）.
选项：
A:voltage series feedback
B:current series feedback
C:current shunt feedback
D:voltage shunt feedback
答案: 【voltage series feedback】

2、单选题：
Calculate the voltage gain for voltage series feedback when the amplifier gain is A = -2000 and F = -1/50.  （    ）
选项：
A:-1/50
B:50
C:-2000
D:-48.78
答案: 【-48.78】

3、单选题：
Calculate the input impedance for voltage series feedback when the amplifier has  = 10 kΩ, amplifier gain is A = -2000, and F= .    （     ）
选项：
A:input impedance with feedback 410 kΩ
B:input impedance with feedback 50 Ω
C:input impedance with feedback 244 Ω
D:input impedance with feedback 10 kΩ
答案: 【input impedance with feedback 410 kΩ】

4、单选题：
The output impedance of current-shunt feedback amplifier （    ） the output impedance of its op-amp.
选项：
A:is reduced by half when compared to
B:is decreased when compared to
C:has no effect on
D:is increased when compared to
答案: 【is increased when compared to】

5、单选题：
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? （     ）
选项：
A:10.59 MHz
B:200 MHz
C:18.88 MHz
答案: 【200 MHz】