2021知到答案 模拟电子技术基础（西安邮电大学版） 智慧树网课章节测试答案
1、选择题:Which of the following is not a commonly used semiconductor material’? （ ）
2、选择题: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、选择题:When a diode is doped with either a pentavalent or a trivalent impurity its resistance will （ ） .
C:make the resistance stable against variation due to temperature
4、选择题: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、选择题:When a p-n junction is reverse-biased, its junction resistance is （ ）.
C:determined by the components that are external to the device
1、选择题:What is the value of the voltage dropped across forward-biased silicon diodes that are connected in parallel with each other? （ ）.
答案: 【0.7 V】
2、选择题: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
答案: 【11 V, 11 mA】
3、选择题:Which of the following circuits is used to eliminate a portion of a signal? （ ）.
4、选择题:The circuit shown here is a （ ）.
答案: 【parallel clipper】
5、选择题:The Zener diode must be operated such that （ ）.
B: is less than the specified
C:the applied voltage is greater than
D:All of these
答案: 【All of these】
1、选择题: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: 【is forward-biased while the base-collector junction is reversed-biased】[$]
2、选择题: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?（ ）.
3、选择题: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)
答案: 【diode drop (about 0.7 V) 】
4、选择题:BJTs are commonly used as （ ）.
A:the primary components in amplifiers
B:series damper circuits
C:the primary components in rectifiers
答案: 【the primary components in amplifiers】
5、选择题:The condition where increase in bias current will not cause further increases in collector current is called （ ）.
1、选择题:When a BJT is biased in the cutoff region the collector-to-emitter voltage is typically equal to （ ）.
A:the emitter voltage
C:the collector current times the collector resistor
D:the collector supply voltage
答案: 【the collector supply voltage 】
2、选择题:Calculate the collector-emitter voltage for this emitter-stabilized circuit.（ ）
答案: 【4.32 V】
3、选择题: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: 【the sign associates with the particular quantities】
4、选择题:The term quiescent means （ ）.
5、选择题: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: 【independent of beta】
1、选择题:Given this configuration, determine the input impedance if VS = 40 mV, Rsense = 0.5 kΩ, and the input current is 20 μA.（ ）
答案: 【1,500 Ω】
2、选择题:The transistor model replaces the （ ） with the junction diode’s ac resistance.
答案: 【emitter—base junction 】
3、选择题:Calculate the voltage gain for this circuit. （ ）
4、选择题: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) （ ）.
答案: 【common-base amplifier】
5、选择题:The voltage gain of a very well-designed common collector amplifier configuration, using a pnp transistor, is （ ）.
C:in the range 0.95 to 0.99
D:in the range -0.95 to -0.99
答案: 【in the range 0.95 to 0.99】
1、选择题:Shockley’s equation defines the （ ） of the FET and are unaffected by the network in which the device is employed.
答案: 【transfer characteristics】
2、选择题:For an n-channel depletion MOSFET, = 8 mA and = -6 V. If = 0.8 V, what is the value of the drain current, ? （ ）
答案: 【10.28 mA】
3、选择题: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: 【the saturation region】
4、选择题:In the family of FETs, you can expect to find （ ）.
A:an n-channel type
B:a p-channel type
答案: 【an n-channel type;
a p-channel type;
5、选择题:FETs usually （ ）.
A:are less sensitive to temperature change than BJTs
B:have a higher input impudence than BJTs
are smaller in construction than BJTs
答案: 【are less sensitive to temperature change than BJTs;
have a higher input impudence than BJTs;
are smaller in construction than BJTs
1、选择题: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
答案: 【self bias for an n-channel JFET】
2、选择题: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: 【the midpoint of the load line】
3、选择题:Which of the following biasing circuits can be used with E-MOSFETs? （ ）
答案: 【drain-feedback bias】
4、选择题: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
D:JFETs can have only positive values of
答案: 【depletion-type MOSFETs can have positive values of and levels of that exceed 】
5、选择题:A JFET can be biased in several different ways. The common method(s) of biasing an n-channel JFET is(are) （ ）.
B:voltage-divider bias configuration
答案: 【self-bias configuration;
voltage-divider bias configuration;
1、选择题:The FET version of the BJT’s common-emitter configuration is the （ ） circuit.
2、选择题:Calculate the input impedance for this FET amplifier. （ ）
D: = would depend on the drain current
3、选择题: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 . （ ）
4、选择题:The （ ） amplifier has high input impedance, low output impedance, and low voltage gain.
5、选择题:The （ ） FET amplifier has low input impedance, high output impedance, and high voltage gain.
1、选择题:Calculate the low frequency break point due to the capacitor for this BJT amplifier. （ ）
2、选择题: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 （ ）.
D:be equal to the sum of all the individual bandwidths
3、选择题:A 3-dB drop in β occurs at （ ）.
4、选择题:Negative dB values represent （ ）.
C:power values that do not change
答案: 【power losses】
5、选择题:An amplifier has a midband power gain of 24,500. What is the value of the power gain in dB for the circuit? （ ）
答案: 【43.9 dB】
1、选择题:Under difference-mode operation, the difference-mode voltage gain for this circuit is （ ）.
2、选择题: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
答案: 【that are common on both the inputs】
3、选择题:The inverting and noninverting inputs to an op-amp are used to drive a(n) （ ） amplifier.
4、选择题: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? （ ）
A:5 : 1
B:5000 : 1
C:1000 : 1
D:5,000,000 : 1
答案: 【5000 : 1】
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
答案: 【the range of frequencies over which gain remains relatively constant ;
the range of frequencies between the lower and upper 3 dB frequencies;
the range of frequencies found using 】
1、选择题: If the input voltage is 0.25 V and the output is -2.5 V, the value of must be （ ）.
答案: 【20.0 kΩ】
2、选择题:The output voltage, VO, is given by （ ）.
3、选择题: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: 【multiple input resistors and feedback capacitors】
4、选择题:A second order low-pass filter has a high-end roll-off of （ ）.
答案: 【40 dB/decade】
5、选择题:An active filter that provides a constant output for input signals above is called an ideal （ ）.
答案: 【high-pass filter】
1、选择题: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: 【conducts through 180° of the input waveform】
2、选择题: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
答案: 【biasing the transistors slightly above cutoff】
3、选择题:The maximum theoretical efficiency of an RC-coupled class A amplifier is （ ）.
4、选择题:Power amplifiers are typically used to drive low impedance loads.（ ）
5、选择题: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.（ ）
1、选择题:The feedback circuit connection shown here is （ ）.
A:voltage series feedback
B:voltage shunt feedback
C:current series feedback
D:current shunt feedback
答案: 【voltage series feedback】
2、选择题:Calculate the voltage gain for voltage series feedback when the amplifier gain is A = -2000 and F = -1/50. （ ）
3、选择题: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
答案: 【input impedance with feedback 410 kΩ】
4、选择题: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
答案: 【is increased when compared to】
5、选择题: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? （ ）
答案: 【200 MHz】[/$]
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