中国大学mooc慕课Analog Electronics Technique(Huazhong University of Science and Technology)1465111447 答案

季捶吨褐妨了碗衬绩伦溶炔蚂

Lecture 1 The Ideal Operational Amplifier Test questions for The Ideal Operational Amplifier

1、 The two input terminals of an operational amplifier are labeled as:

A:high and low
B:positive and negative
C:inverting and noninverting
D:differential and nondifferential
答案: inverting and noninverting

2、 For the circuit in  the Figure, the output voltage vo is (    ).

A:-6V
B:-5V
C:-1V
D:-0.2V
答案: -5V

3、 For the circuit in Figure, the current ix is (    )

A:0.6mA
B:0.5mA
C:0.2mA
D:1/12 mA
答案: 0.5mA

4、 For the circuit in Figure, current io is(     )

A:-10 μA
B:-2.5 μA
C:10/12 μA
D:10/14 μA
答案: -10 μA

5、 If vs=8 mV, in the circuit of Figure, the output voltage is(     )

A:-44 mV
B:-8 mV
C:4 mV
D:7 mV
答案: 4 mV

6、 The power absorbed by the 4k ohm resistor in Figure is(     ).

A:9 mW
B:4 mW
C:2 mW
D:1 mW
答案: 4 mW

7、 For the circuit in Figure,the output voltage v0 is(    ).

A:3 V
B:-3 V
C:-1 V
D:-2 V
答案: -3 V

8、 For the circuit in Figure,the output current io is(    ).

A:0.2 mA
B:-0.2 mA
C:0.1 mA
D:-0.1 mA
答案: -0.2 mA

9、 For the circuit in Figure,the output voltage vo is(    ).

A:5V
B:-5V
C:3.75V
D:-3.75V
答案: -5V

10、 For the circuit in Figure,the output voltage vo is (    )

A:5 V
B:-5 V
C:8 V
D:-8 V
答案: -8 V

11、 For the circuit in Figure,the output voltage vo is  (    ).

A:5 V
B:-5 V
C:3.8 V
D:-3.8 V
答案: -3.8 V

12、 Assume the operational amplifiers are ideal,if the input voltage is +1V，Determine vo=(      ).

A:1 V
B:-1 V
C:2 V
D:0 V
答案: 2 V

13、 Assume the operational amplifiers are ideal,Determine vo=(    );

A:1 V
B:-1 V
C:2 V
D:0 V
答案: 0 V

14、 For the circuit in Figure,the output voltage vo is(    )

A:150 mV
B:250 mV
C:350 mV
D:450 mV
答案: 350 mV

15、 For the circuit in Figure,the output voltage vo is(    )

A:3.2 V
B:-0.8 V
C:2.4 V
D:1.2 V
答案: 2.4 V

16、 For the circuits shown as Figure, assume the op-amps is ideal, and the maximun output voltage of all of the op-amps is ±13V, when time is t=0s, give the input voltage is a step in voltage, and the amplitude of the input is 100mV, when time is t=1s, determine the output voltage of each op-amp is(    ).

A:13 V
B:-13 V
C:0 V
D:100 mV
答案: 0 V

17、 For the circuit in the Figure, the op-amps are ideal, the input  resistances of the two circuits are (   )

A:Ri1=Ri2=1k ohm
B:Ri1<Ri2
C:Ri1>Ri2
D:Ri1=Ri2=∞
答案: Ri1<Ri2

18、 Assume  all the Op-Amps are ideal, determine vo in terms of vi is  （    ）

A:vo=-0.5(vi+5)
B:vo=0.5(vi+5)
C:vo=2(vi+5)
D:vo=-2(vi+5)
答案: vo=0.5(vi+5)

19、 Determine the voltage transfer ratio vo/vs in this op-amp circuit, where R=10k ohm.

A:-1/3
B:-2/3
C:1/3
D:2/3
答案: -2/3

20、 Assume  all the Op-Amps are ideal, and when time t=0, the capacitor voltage vc=0, then when t=0, vo1=(     ), vo2=(    ).

A:vo1=4V,vo2=1V;
B:vo1=-4V,vo2=-1V;
C:vo1=7V, vo2=1V;
D:vo1=7V, vo2=-2V
答案: vo1=7V, vo2=-2V

21、 Assume  all the Op-Amps are ideal, and when time t=0, the capacitor voltage vc=0, then when t=( ? )s,  the output voltage vo=0.

A:1
B:1/70
C:1/35
D:2
答案: 1/35

22、 For an ideal op amp, which of the following statements are not true?

A:The differential voltage across the input terminals is zero
B:The current into the input terminals is zero.
C:The current from the output terminal is zero
D:The input resistance is zero
E:The output resistance is zero
答案: The current from the output terminal is zero;
The input resistance is zero

23、 Difference amplifiers maybe used in (    ).

A:instrumentation amplifiers
B:voltage followers

C:buffers

D:summing amplifiers

E:subtracting amplifiers

答案: instrumentation amplifiers;

subtracting amplifiers

24、 In the linear operational amplifiers circuit, the inverting input of the operational amplifier is virtual ground.

A:正确
B:错误
答案: 错误
分析：only in inverting amplifiers is virtual ground, in the noninverting amplifiers not like this.

25、 The voltage gain of the voltage follower is 1, so it can be replaced by a wire.

A:正确
B:错误
答案: 错误
分析：the voltage follower can eliminate loading effect, not like the wire.

26、 In the case of open-loop, the integrated operational amplifier must work in the non-linear region.

A:正确
B:错误
答案: 正确
分析：Because the voltage gain of the op-amp is very very large, so if no negative feedback, the op-amp can not work in linear region.

27、 Assume  all the Op-Amps are ideal, determine vo is  （    ）V.
答案: 5
分析：you can understand this question with superposition, when v3 is set to zero, you can find vo1=-30k/30k(-3V)+(-30k/30k)4V=1V, then set v1=v2=0, and the circuit is noninveting amp. the output is 3V[30/(30+15)] (1+30/(30||30)=2V*3=6V, then output is 6-1=5V.

Lecture 2 Semiconductor Materials and Diodes Circuits Test questions for Semiconductor Materials and

1、 At room temperature, the concentration relationship between free electrons and holes in intrinsic semiconductors is as follows （   ）

A:Undetermined
B:More free electrons
C:More holes
D:Same
答案: Same

2、 What are the majority carriers in n-type materials?

A:holes
B:free electrons
C:Positive ions
D:Negative ions
答案: free electrons

3、 What are the minority carriers in p-type materials?

A:holes
B:free electrons
C:Positive ions
D:Negative ions
答案: free electrons

4、 After the formation of PN junction, the relationship between diffusion current and drift current is as follows （   ）

A:More  diffusion current
B:More  drift current
C:Same
D:Undetermined
答案: Same

5、 When PN junction is reverse biased, the resistance becomes  （  ）

A:smaller
B:larger
C:Unchanged
D:Undetermined
答案: larger

6、 When the PN junction is forward biased , the current is  mainly（   ）

A:Reverse drift current
B:Forward diffusion current
C:Forward drift current
D:Reverse diffusion current
答案: Forward diffusion current

7、 For the circuit shown in Figure， when Vγ=0.7V， the diode voltage VD and the current ID are （    ）

A:VD=0.7V, ID=1mA
B:VD=0.5V, ID=1mA
C:VD=0.5V, ID=0mA
D:VD=0.7V,ID=0mA
答案: VD=0.5V, ID=0mA

8、 When the temperture T increases， the forward voltage of the PN junction (    )

A:Increase
B:Decrease
C:unchanged
D:uncertain
答案: Decrease

9、 The concentration of the majority carriers in the extrinsic semiconductor is mainly affected by (     ).

A:The concentration of impurity
B:The temperature
C:The crystal defect
D:The doping technology
答案: The concentration of impurity

10、 The concentration of the minority carriers in the extrinsic semiconductor is mainly affected by (     )

A:The concentration of impurity 
B:The temperature
C:The crystal defect
D:The doping technology
答案: The temperature

11、 The zener diode circuit is shown as figure, if VI =10V，R =100ohm，VZ =5V，IZ(min)=5mA，IZ(max)=50mA,T、then the reisitance of RL should be  (   )

A:> 111 ohm
B:< 111 ohm
C:> 111 k ohm
D:< 111 k ohm
答案: > 111 ohm

12、 The circuit is shown as figure, and VDD = 2 V，R = 1 kohm,vs=50sin(2pi*50t)mV，and Vγ=0.7V, then the quiescent current of the diode is (    ), the quiescent voltage of the output vO is  (    ) , and the ac voltage amplitude of the output is (   ) .

A:2mA，2V；0.05V
B:1.3mA，1.3V；0.05V
C:2mA，2V；0.049V
D:1.3mA，1.3V；0.049V
答案: 1.3mA，1.3V；0.049V

13、 The circuit is shown as figure, the input voltages are shown in the table, the output voltage should be (   )

A:a
B:b
C:c
D:d
答案: b

14、 The circuit is shown as figure,the diodes are silicon diodes, when vs = 6sinwt V, please use the case1 model (Vr=0.7V) to analysis the circuit, the output waveform should be (    ) 

A:a
B:b
C:c
D:d
答案: b

15、 The circuit is shown as figure , if the RMS value of the ac sine signal is 220V, RL = 0.1k,we use the ideal model to analysis the circuit, then the peak inverse voltage of the diode is (   ).The  maximum rectified current of the diode is (   ).

A:220V，0.99A
B:220V，1.98A
C:311V，1.98A
D:311V，0.99A
答案: 311V，0.99A

16、 For the circuit shown as figure, if we use ideal model, and the amplitude of the ac sine signal is 24V, then the peak current of the diode is(    ), and the peak inverse voltage of the diode is(    ）

A:240mA，24V
B:120mA，12V
C:120mA，36V
D:360mA，36V
答案: 120mA，36V

17、 The circuit is shown as figure,the diodes are silicon diodes, and Vr=0.7V, the diodes D1 and D2 should be (    ). 

A:D1 on, D2 on;
B:D1 on, D2 off
C:D1 off, D2 off
D: D1 off,D2 on
答案:  D1 off,D2 on

18、 The circuit is shown as figure, the load voltage is VL=9V, aand the input voltage maybe vary between 11 and 13.6V, the current of the load will vary from 0 to 100mA, the the maximum current of the zener diode is (   )

A:100mA
B:200mA
C:300mA
D:400mA
答案: 300mA

19、 In order to form n-type semiconductors, What elements can you add (   )

A:B
B:C
C:Al
D:Si
E:P
F:Ga
G:Ge
H:As
答案: P;
As

20、 In order to form p-type semiconductors, What elements can you add (   )

A:B
B:C
C:Al
D:Si
E:P
F:Ga
G:Ge
H:As
答案: B;
Al;
Ga

21、 For the actual diode, as long as the positive bias voltage is greater than zero, the diode will turn on.

A:正确
B:错误
答案: 错误
分析：must greater than turn on voltage.

22、 When using zener diodes, current limiting resistors are not required.

A:正确
B:错误
答案: 错误
分析：must need this resistor to adjust voltage.

23、 For general diodes, LEDs and photodiodes, forward bias voltage is required for normal operation.

A:正确
B:错误
答案: 错误
分析：photoiodes usually is reverse biased.

Lecture 3 The Field-Effect Transistor Test questions for The Field-Effect Transistor

1、 For a p-channel Enhancement-Mode MOSFET, to create an inversion layer,we must add what gate to source voltage VGS? 

A:Positive
B:Negative
C:Arbitrary
D:Indeterminate
答案: Negative

2、 The drain current  of the MOSFET is formed by the (         ） drift movement ?

A:majority carrier
B:minority carrier
C:two carriers
D:Indeterminate
答案: majority carrier

3、 The drain current  of the MOSFET is controlled by the （   ）

A:the gate current iG
B:the gate to source voltage VGS
C:the darin to source voltage VDS
D:the gate to drain voltage VGD
答案: the gate to source voltage VGS

4、 The drain current versus gate-to-source voltage characteristics is shown in Figure, the FET should be (   ).

A:Enhancement-mode NMOSFET
B:Enhancement-mode PMOSFET
C:Depletion-mode NMOSFET
D:Depletion-mode PMOSFET
答案: Enhancement-mode NMOSFET

5、 For the circuits shown in Figure, find which circuit can work as an amplifier (     ).

A:A
B:B
C:C
D:D
答案: D

6、 The drain current versus gate-to-source voltage characteristics is shown in Figure， and for the MOSFET , the voltage of the three terminals are: VS=-5V,VG=1V,VD=3V, the work region of this MOSFET is (     ).

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: saturation

7、 The threshold voltage of the MOSFET in the circuit is VTN=1V, not consider the voltage drop of the drainresistor, Determine the work region of the MOSFET in the circuit. （    ）

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: saturation

8、 The threshold voltage of the MOSFET in the circuit is VTP=-1V, not consider the voltage drop of the drain resistor, Determine the work region of the MOSFET in the circuit. (    )

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: cutoff

9、 In the circuit in Figure， VGSQ=（    ）V，ID=（   ）mA，VDS=(    )V;

A:VGSQ=1V,IDQ=1mA,VDSQ=3V;
B:VGSQ=2V,IDQ=0.1mA,VDSQ=3V;
C:VGSQ=1V,IDQ=0.1mA,VDSQ=3V;
D:VGSQ=2V,IDQ=1mA,VDSQ=3V;
答案: VGSQ=2V,IDQ=0.1mA,VDSQ=3V;

10、 In the circuit in Figure，the MOSFET worked in which Region? (     )

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: saturation

11、 In the circuit in Figure，the MOSFET worked in which Region? (     )

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: nonsauration

12、 In the circuit in Figure， VGSQ=（    ）V，ID=（   ）mA，VDS=(    )V;

A:VGSQ=4V,IDQ=4mA,VDSQ=-2V;
B:VGSQ=4V,IDQ=1mA,VDSQ=7V;
C:VGSQ=3V,IDQ=1mA,VDSQ=6V;
D:VGSQ=4V,IDQ=1mA,VDSQ=3V;
答案: VGSQ=3V,IDQ=1mA,VDSQ=6V;

13、 In the circuit in Figure， VGSQ=（    ）V，ID=（   ）mA，VDS=(    )V;

A:VGSQ=4V,IDQ=4mA,VDSQ=-2V;
B:VGSQ=4V,IDQ=1mA,VDSQ=7V;
C:VGSQ=3V,IDQ=1mA,VDSQ=6V;
D:VGSQ=3V,IDQ=1mA,VDSQ=2.5V;
答案: VGSQ=3V,IDQ=1mA,VDSQ=2.5V;

14、 In the circuit in Figure，the MOSFET worked in which Region? (     )

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: saturation

15、 In the circuit in Figure，the MOSFET worked in which Region? (     )

A:cutoff
B:saturation
C:nonsauration
D:Indeterminate
答案: saturation

16、 In the circuit in Figure， VGSQ=（    ）V，ID=（   ）mA，VDS=(    )V;

A:VGSQ=2V,IDQ=2mA,VDSQ=2.8V;
B:VGSQ=2.2V,IDQ=1mA,VDSQ=7.2V;
C:VGSQ=2V,IDQ=2mA,VDSQ=6V;
D:VGSQ=2.2V,IDQ=1mA,VDSQ=2.2V;
答案: VGSQ=2.2V,IDQ=1mA,VDSQ=7.2V;

17、 Which MOSFETs can work as amplifiers in the following circuits.

A:A
B:B
C:C
D:D
E:E
答案: B;
D

18、 The gate source voltage and the drain source voltage are as follows, and  VTN, VTP or VPN, VPP values are also known.which MOSFETs work in cutoff region （    ）

A:VDS＝3V， VGS＝2V， VTN＝1V
B:VDS＝3V， VGS＝1V， VTN＝1.5V
C:VDS＝3V， VGS＝－1V， VPN＝－2V
D:VDS＝－3V， VGS＝－2V， VTP＝－1V
E:VDS＝3V， VGS＝－2V， VTP＝－1V
F:VDS＝－3V， VGS＝－1V， VTP＝－1.5V
答案: VDS＝3V， VGS＝1V， VTN＝1.5V;
VDS＝3V， VGS＝－2V， VTP＝－1V;
VDS＝－3V， VGS＝－1V， VTP＝－1.5V

19、 The gate source voltage and the drain source voltage are as follows, and  VTN, VTP or VPN, VPP values are also known.which MOSFETs work in saturation region （    ）

A:VDS＝3V， VGS＝2V， VTN＝1V
B:VDS＝3V， VGS＝1V， VTN＝1.5V
C:VDS＝3V， VGS＝－1V， VPN＝－2V
D:VDS＝－3V， VGS＝－2V， VTP＝－1V
E:VDS＝3V， VGS＝－2V， VTP＝－1V
F:VDS＝－3V， VGS＝－1V， VTP＝－1.5V
答案: VDS＝3V， VGS＝2V， VTN＝1V;
VDS＝3V， VGS＝－1V， VPN＝－2V;
VDS＝－3V， VGS＝－2V， VTP＝－1V

20、 For n-channel and p-channel MOSFETs, the drain source voltage VDS can be positive or negative value.

A:正确
B:错误
答案: 错误
分析：For n channel,VDS>0, but for p-channel, VDS<0;

21、 For n-channel depletion-mose MOSFETs, the gate source voltage VGS must be positive in order to get the MOSFETs work in the saturation region.

A:正确
B:错误
答案: 错误
分析：for depletion-mode, the VGS can be negative value.

22、 The threshold voltage of p-channel and n-channel enhancement-mode MOSFETs must be positive.

A:正确
B:错误
答案: 错误
分析：For n channel,threshold voltage>0, but for p-channel, threshold voltage<0;

Lecture 4 Basic FET Amplifiers Test questions for Basic FET Amplifiers

1、 Assuming that the capacitors in the circuit are very large and can be regarded as short circuit to AC signal, the small signal equivalent circuit is （    ）? 

A:
B:
C:
D:
答案:

2、 Assuming that the DC operating points of all the following amplifier circuits are normal, all of the capacitors to AC signal can be regarded as a short circuit, and the circuit with the largest input resistance is （    ）.

A:
B:
C:
D:
E:
答案:

3、 Assuming that the DC operating points of all the following amplifier circuits are normal, all of the capacitors to AC signal can be regarded as a short circuit, and which circuit has the lowest input resistance （    ）

A:
B:
C:
D:
E:
答案:

4、 Assuming that the DC operating points of all the following amplifier circuits are normal, all of the capacitors to AC signal can be regarded as a short circuit, and which circuit has the lowest output resistance （    ）

A:
B:
C:
D:
答案:

5、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. The gm of T1 is gm=1mS.Determine the voltage gain of the circuit Av=vo/vi=（    ）

A:3.3
B:-3.3
C:-10
D:-0.77
答案: -3.3

6、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. Determine the voltage gain of the circuit Av=vo/vi=（    ）

A:3
B:-3
C:6
D:-6
答案: -3

7、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. Determine the voltage gain of the circuit Av=vo/vi=（    ）

A:3
B:-3
C:1
D:-1
答案: -1

8、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. Determine the voltage gain of the circuit Av=vo/vi=（    ）

A:3
B:-3
C:6
D:-6
答案: -6

9、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. Determine the voltage gain of the circuit Av=vo/vi=（    ）.

A:6
B:-6
C:2
D:-2
答案: -2

10、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. Determine the voltage gain of the circuit Av=vo/vi=（    ）

A:3
B:-3
C:6
D:-6
答案: -3

11、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. Determine the voltage gain of the circuit Av=vo/vi=（）.

A:-0.89
B:0.89
C:10
D:-10
答案: 0.89

12、 Assuming that the DC operating points of all the following amplifier circuits are normal, all of the capacitors to AC signal can be regarded as a short circuit, and which circuits have output and input signals in phase（    ）

A:
B:
C:
D:
E:
答案: ;

13、 Assuming that the DC operating points of all the following amplifier circuits are normal, all of the capacitors to AC signal can be regarded as a short circuit, and which circuits have output and input signals opposite phase（    ）

A:
B:
C:
D:
E:
答案: ;
;

14、 In the multistage amplifier circuit, the input resistance is the input resistance of the first stage, and the output resistance of the amplifier circuit is equal to the output resistance of the last stage (output stage).

A:正确
B:错误
答案: 正确

15、 Because the voltage gain of common drain amplifier circuit is less than 1, it cannot be used in the amplifier circuit

A:正确
B:错误
答案: 错误
分析：The input resistance of the CD amplifier is very large, it can be used to active load, imporve the first stage voltage gain.

16、 Because the structures of n-channel enhancement MOSFET and p-channel enhancement MOSFET are different, the DC bias of amplifier circuit is different, and the small model used in AC analysis is also different.

A:正确
B:错误
答案: 错误
分析：The DC bias of amplifier circuit is different, but the small model used in AC analysis is same.

17、 The field effect transistor (FET) works in the saturation region and can be used as an amplifier. The AC amplification performance is independent of the DC operating point.

A:正确
B:错误
答案: 错误
分析：The ac parameters gm and ro are determine by DC point.

18、 The threshold voltage and transconductance of enhancement MOSFET are constant.

A:正确
B:错误
答案: 错误
分析：The threshold voltage is constant, but gm is determine by q-point.

19、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit. The gm of T1 is gm=1mS.Determine the input resistance is（    ）kohm.
答案: 2075
分析：Ri=Rg3+Rg1||Rg2=2000k+100k||300k=2075k ohm

20、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit.Determine the output resistance is (   ) ohm.
答案: 500
分析：gm=2root(KnIDQ)=2root(11)=2mS, Ro=1/gm=1/2mS=500 ohm.

21、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit.Determine the input resistance is (   )ohm.
答案: 1000
分析：gm=2root(KnIDQ)=2root(0.50.5)=1mS, Ro=1/gm=1/1mS=1000 ohm.

22、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit.Determine the source voltage gain of the circuit Av=vo/vs=(   ).
答案: 5
分析：gm=2root(KnIDQ)=2root(0.50.5)=1mS,Av=gmRd=1ms10k ohm=10, for the source, AVS=AvRi/(Ri+Rsi)=101/(1+1)=5.

23、 The circuit is as shown in the figure, and the capacitance in the passband can be regarded as a short circuit.Determine the output resistance is (   )k ohm.
答案: 10
分析：For CG amplifier, the output resistance just Rd.

Lecture 5 The Bipolar Junction Transistor Test questions for The Bipolar Junction Transistor

1、 When a BJT transistor is used as an amplifying device, the base-emitter junction is (     ) biased, and the base-collector junction is (    ) biased.

A:Forward，forward
B:Reverse,  reverse
C:Forward, reverse
D:Reverse, forward
答案: Forward, reverse

2、 For the impurity doping concentrations in the three regions of the BJT, which region is the highest (    )

A:base
B:emitter
C:collect
D:unidentified
答案: emitter

3、 When a BJT transistor worked in saturation region, the base-emitter junction is (     ) biased, and the base-collector junction is (    ) biased.

A:Forward，forward
B:Reverse,  reverse
C:Forward, reverse
D:Reverse, forward
答案: Forward，forward

4、 A transistor is biased in the forward-active mode, the current of the three terminals are I1= –1.2mA,  I2= –0.03mA, I3= 1.23mA，which of these is the emitter terminal (    )，and which of these is the base terminal (    )

A:1，2
B:2，3
C:3,2
D:3,1
答案: 3,2

5、 In a BJT circuit, the transistor are made of silicon, and the voltage values for three terminals are given, which BJT operates in forward-active mode (    )

A:VC=6V ,VB=0.7V, VE=0V
B:VC=6V , VB=6V , VE=5.4V
C:VC=6V ,VB=4V ,VE=3.6V
D:VC=3.6V ,VB=4V ,VE=3.4V
答案: VC=6V ,VB=0.7V, VE=0V

6、 In a BJT circuit, the transistor are made of silicon, and the voltage values for three terminals are given, which BJT operates in cutoff region (    )（For silicon transistor，we think VBE（th）=0.5V）

A:VC=6V ,VB=0.7V, VE=0V
B:VC=6V , VB=6V , VE=5.4V
C:VC=6V ,VB=4V ,VE=3.6V
D:VC=3.6V ,VB=4V ,VE=3.4V
答案: VC=6V ,VB=4V ,VE=3.6V

7、 In the amplification circuit, the BJT is worked in forward-active region, and the voltage of each terminals is V1=2V, V2=6V and V3=2.7V, for the three terminals, which is the emitter (      ), the type of this transistor is (     ).

A:3, NPN
B:2, PNP
C:1,NPN
D:1, PNP
答案: 1,NPN

8、 For the circuit shown in Figure, which region does the transistor work in (    )

A:Forward-active region
B:Saturation region
C:Cutoff region
D:unidentified
答案: Saturation region

9、 For the circuit shown in Figure, which region does the transistor work in (    )

A:Forward-active region
B:Saturation region
C:Cutoff region
D:unidentified
答案: Forward-active region

10、 For the circuit shown in Figure, which region does the transistor work in (    )

A:Forward-active region
B:Saturation region
C:Cutoff region
D:unidentified
答案: Forward-active region

11、 For the circuit shown in Figure, if the input signal is a good sinusoidal signal, but the output waveform is in the Figure 16, so this is which distortion (   )

A:no distortion
B:Saturation region
C:Cutoff region
D:unidentified
答案: Saturation region

12、 A transistor is biased in the forward-active mode, the current of the three terminals are  I1= –1.2mA, I2= –0.03mA, I3= 1.23mA，the current gain β is (    )

A:30
B:40
C:50
D:60
答案: 40

13、 In a BJT circuit, the transistor are made of silicon, and the voltage values for three terminals are given, which BJT operates in saturation region (    )

A:VC=6V ,VB=0.7V, VE=0V
B:VC=6V , VB=6V , VE=5.4V
C:VC=6V ,VB=4V ,VE=3.6V
D:VC=3.6V ,VB=4V ,VE=3.4V
答案: VC=6V , VB=6V , VE=5.4V;
VC=3.6V ,VB=4V ,VE=3.4V

14、 For the circuit shown in Figure, if the input signal is a good sinusoidal signal, but the output waveform is in the Figure, so what measures can be taken to eliminate such distortion (   )

A:increase VCC amplitude
B:reduce the amplitude of signal source
C:reduce the value of load resistance RL
D:open the load
答案: increase VCC amplitude;
reduce the amplitude of signal source;
reduce the value of load resistance RL

15、 If the emitter and collector of BJT transistor are exchanged, the amplifier can still be constructed.

A:正确
B:错误
答案: 错误

16、 When NPN transistor works in the forward active region, generally we added positive power supply, but for PNP transistor, we must add negative power supply.

A:正确
B:错误
答案: 错误

17、 For the circuit shown in Figure, the operational amplifier is assumed to be ideal, for the transistor VBE=VB-VE=0.7V, if the reading of the voltmeter is 200mV,then the current gain β of the transistor is (    )
答案: 50

Lecture 6 Basic BJT Amplifiers Test questions for Basic BJT Amplifiers

1、  For the circuit shown in Figure, determine the small signal hybrid-π resistance rπ is (    )and the voltage gain is （     ）

A:2.6k ohm,200
B:2.6k ohm, -200
C:2.6 ohm, 200000
D:2.6 ohm, -200000
答案: 2.6k ohm, -200

2、 For all of the circuits shown in Figure, which circuit can amplify AC small signal (    )

A:(a)
B:(b)
C:(c)
D:(d)
答案: (b)

3、 For the circuit shown in Figure, which position is the switch in A, B, C? the transistor can work in the forward active region (    )

A:A
B:B
C:C
D:Unable to determine
答案: B

4、 For the circuit shown in Figure, if the transistor works in the forward active region, which output waveform is correct (    )

A:
B:
C:
D:
答案:

5、 For the circuit shown in Figure, if the transistor works in the forward active region, which outputwaveform is correct (    )

A:
B:
C:
D:
答案:

6、 If the source resistance of the signal source is 1kohm，and when the amplifying circuit is not connected,the voltage amplitude of the signal source is 10mV， but when the amplifying circuit is connected,the voltage of the input port of the amplifying circuit is 8mV， then the input resistance of the amplifying circuit is (     )k ohm.

A:5
B:4
C:2
D:1
E:0.5
答案: 4

7、 For the amplifier, when the load is open,the output voltage is 4V, and when the 3k ohm load resistor is connected, the output voltage is 3V, then the output resistance of the amplification circuit is (    )k ohm.

A:5
B:4
C:2
D:1
答案: 1

8、 For the amplifier, when the input signal is 10pA current and the output is 500mV voltage, the input resistance of this amplifier is better if it is larger or smaller, and the the output resistance of this amplifier is better if it is larger or smaller(    )

A:smaller,larger
B:smaller, smaller
C:larger, larger
D:larger, smaller
答案: smaller, smaller

9、 For the circuit shown in Figure，the voltage gain is （     ）,and the input resistance is (   )k ohm, output resisdtance is  (    ) k ohm.

A:145,300,1
B:-145, 0.69,2
C:290,0.69,2
D:-145,0.69,1
答案: -145, 0.69,2

10、 For the circuit shown in Figure，the voltage gain is （     ）,and the input resistance is (   )k ohm, output resisdtance is  (    ) k ohm.

A:87,1.55,3
B:-87, 1.55,3
C:174,1.55,1.5
D:-174,1.55,1.5
答案: -87, 1.55,3

11、 For the circuit shown in Figure，when the 50uF capacitor is open, the the voltage gain is will (     ) and the input resistance will (   ), output resisdtance will (    ).

A:increase, decrease, unchanged 
B:decrease, increase, unchanged
C:decrease,decrease,decrease
D:increase,increase,increase
答案: decrease, increase, unchanged

12、 For the circuit shown in Figure ，the voltage gain is （     ）,and the input resistance is (   )k ohm, output resisdtance is  (    )  ohm.

A:0.99,87.2,5.1k
B:0.99, 87.2, 33
C:0.99,260,2.55k
D:99,87.2,2.55k
答案: 0.99, 87.2, 33

13、 For the circuit shown in Figure，when the ouput voltage is Vo1, the source voltage gain Vo1/vs is （     ）,and the input resistance is (   )k ohm, output resisdtance is  (    )  ohm.

A:0.79,82,2k
B:-0.79, 8.2, 2k
C:0.8,82,31
D:-0.8,8.2,1k
答案: -0.79, 8.2, 2k

14、 For the circuit shown in Figure ，when the ouput voltage is Vo2, the source voltage gain is （     ）,and the input resistance is (   )k ohm, output resisdtance is  (    )  ohm.

A:0.79,82,2k
B:-0.79, 8.2, 2k
C:0.8,8.2,31
D:-0.8,8.2,1k
答案: 0.8,8.2,31

15、 For the circuit shown in Figure，the voltage gain is （     ）,and the input resistance is (   )k ohm, output resisdtance is  (    )  ohm.

A:-291,2.574,7.5k 
B:291, 25, 7.5k
C:-291,0.025,7.5k
D:291,0.025,7.5k
答案: 291,0.025,7.5k

16、 In the following circuits,which circuit has the least input resistance (    )

A:
B:
C:
D:
答案:

17、 In the following circuits,which circuit has the least output resistance.(    )

A:
B:
C:
D:
答案:

18、 In the following circuits,which circuit has the largest absolute gain. (     )

A:
B:
C:
D:
答案:

19、 For the circuit shown in Figure, if the DC voltage VCE≈VCC, what may be wrong with the circuit?

A:The capacitor Cb1 is short
B:The resistor Rb is open
C:The resistor  RC is short
D:The resistor  Rb is short
E:The resistor  RC is open
答案: The capacitor Cb1 is short;
The resistor Rb is open;
The resistor  RC is short

20、 For the circuit shown in Figure, if the transistor works in the forward active region, which small signal equivalent circuit is correct (    )

A:
B:
C:
D:
E:
F:
答案: ;

21、 Which of the following amplifying circuits may amplify the signal AC voltage (    )

A:CE
B:CC
C:CB
D:CS
E:CD
F:CG
答案: CE;
CB;
CS;
CG

22、 Which of the following amplifying circuits may amplify the signal AC current (    )

A:CE
B:CC
C:CB
D:CG
E:CD
F:CS
答案: CE;
CC

23、 In the following circuits,which circuits have output voltage and input voltage in phase.(     )

A:
B:
C:
D:
答案: ;
;

24、 In the following circuits,which circuits have inverse output and input voltages.(    )

A:
B:
C:
D:
E:
答案: ;

25、 When a BJT transistor is biased in the forward-active mode, then iC=β* iB, so we can think oftransistors as always linear devices.

A:正确
B:错误
答案: 错误

26、 Use the BJT, we can magnify an input small signal to a large output signal, we don’t need DC power supply.

A:正确
B:错误
答案: 错误

27、 As long as the transistor works in the forward active region, no matter how large the input signal is, linear amplification can be realized.

A:正确
B:错误
答案: 错误

28、 Because of the different structure of NPN and PNP, the DC biasing is different when they work in forward active region, so the small signal model is different

A:正确
B:错误
答案: 错误

29、 The capacitor can be open for dc, and can be short for any signal frequency.

A:正确
B:错误
答案: 错误

30、 The independent source can always become a short circuit for ac analysis.

A:正确
B:错误
答案: 错误

31、 For the BJT, when the Early voltage VA is not infinite， we’re dealing with small-signal amplifiers, we also say that the collector current of a BJT in active mode is equal to the base current multiplied by β.

A:正确
B:错误
答案: 错误

32、 For the circuit with emitter bypass capacitor, this bypass capacitor not only changes the Q-point, but also affects the small signal voltage gain.

A:正确
B:错误
答案: 错误

33、 Because the small signal voltage gain of the common collector circuit is less than 1, it has no contribution to signal amplification.

A:正确
B:错误
答案: 错误

34、 The common collector circuit can neither amplify voltage nor current.

A:正确
B:错误
答案: 错误

35、 For the circuit shown in Figure ，whether the output voltage waveform is correct（     ）

A:正确
B:错误
答案: 错误