大学MOOC Microelectronics Devices(University of Electronic Science and Technology of China)1458227165 最新慕课完整章节测试答案

3.7.1

1、判断题：
‏With the increase of frequency, the current amplification ability of transistor will reduce or even lose.​‏​‏​
选项：
A: 正确
B: 错误
答案: 【 正确】

3.7.2

1、多选题：
‌tb is called (  ).‎‌‎
选项：
A: Base transit time
B: Charging and discharging time constant of emitter diffusion capacitor
C: Charging and discharging time constant of barrier diffusion capacitor
D: Charging and discharging time constant of collector barrier capacitance
答案: 【 Base transit time;
Charging and discharging time constant of barrier diffusion capacitor】

2、判断题：
‍​‍The ratio of ic to ie under high frequency and small signal conditions when the output terminal is short circuited（vcb = 0，VCB < 0） is called the common-base highf-requency small-signal short-circuit current gain, which is recorded as αω.​‍​‍​
选项：
A: 正确
B: 错误
答案: 【 正确】

3.7.3

1、判断题：
‏When |αω| decreases to (i.e. 3 dB) α0/√2，the corresponding angular frequency and frequency are respectively called the cut-off angular frequency and cut-off frequency of αω, which are recorded as ωα and fα​‏​
选项：
A: 正确
B: 错误
答案: 【 正确】

2、判断题：
​Every time the frequency is doubled, the current gain factor of bipolar transistor is reduced by half and the power gain of bipolar transistor is reduced by quarter‏​‏
选项：
A: 正确
B: 错误
答案: 【 正确】

3.7.4

1、判断题：
‎When the current amplification factor |βω| drops to 1, the corresponding frequency is called the characteristic frequency of the transistor, which is recorded as fT. ‍‎‍
选项：
A: 正确
B: 错误
答案: 【 正确】

2、判断题：
‏The product of current gain |βω| and frequency f at high frequency is a constant independent of frequency and completely depends on the transistor itself​‏​
选项：
A: 正确
B: 错误
答案: 【 正确】

3.9

1、判断题：
‎The product of the power gain and the square of frequency is called the high-frequency figure of merit，denoted as M. ‍‎‍
选项：
A: 正确
B: 错误
答案: 【 正确】

2、判断题：
‎When the maximum power output gain drops to 1, the corresponding frequency is called the maximum oscillation frequency, denoted as fM.​‎​
选项：
A: 正确
B: 错误
答案: 【 正确】

4.1.1

1、多选题：
‎Which of the following devices belong to majority carrier- type device?  (  )‏‎‏
选项：
A: PN junction diode
B: junction-gate field effect transistor
C: bipolar transistor
D: insulated gate field effect transistor
答案: 【 junction-gate field effect transistor;
insulated gate field effect transistor】

4.1.2

1、判断题：
‌‍‌‍‌‍‌ If the threshold voltage of a P-channel MOSFET is higher than zero, the device is an enhancement mode device.‍‌‍‌‍
选项：
A: 正确
B: 错误
答案: 【 错误】

4.2.1

1、判断题：
‎When the concentration of minority carrier on the silicon surface is equal to or higher than that of majority carrier on the surface, the surface is said to be in the strong inversion state.‌‎‌
选项：
A: 正确
B: 错误
答案: 【 错误】

4.2.2

1、多选题：
‍The factors affecting MOSFET threshold voltage include (   )‍‍‍
选项：
A: gate oxide thickness 
B: channel width
C: doping concentration of substrate
D: oxide fixed charge
答案: 【 gate oxide thickness ;
doping concentration of substrate;
oxide fixed charge】

2、判断题：
‌For an N-type MOSFET, in order to guarantee the device working properly, the substrate potential should be equal to or lower than the source potential.‎‌‎
选项：
A: 正确
B: 错误
答案: 【 正确】

4.3.1

1、单选题：
‎Which of the following measures can increase the drain current in MOSFET saturation region: ‍‎‍
选项：
A:  Increasing the channel length
B: Reducing the gate oxide thickness
C: Reducing the channel width
D: Improving the threshold voltage
答案: 【 Reducing the gate oxide thickness】

2、多选题：
‎In the derivation of DC current and voltage equation of MOSFET, which of the following approximations are used:‎‎‎
选项：
A: gradual channel approximation
B:  strong inversion approximation 
C: depletion approximation 
D: channel mobility constant approximation
答案: 【 gradual channel approximation;
 strong inversion approximation ;
channel mobility constant approximation】

4.3.2

1、多选题：
‎The drain current ID in the saturation region of MOSFET increases slightly with the increase of VDS, which is caused by :‍
选项：
A: base region width modulation effect
B: feedback of electrostatic field in drain region to the channel
C: effective channel modulation effect
D: short channel effect of threshold voltage
答案: 【 feedback of electrostatic field in drain region to the channel;
effective channel modulation effect】

4.4

1、单选题：
‌Which of the following measures can reduce the subthreshold swing of MOSFET ?​‌​
选项：
A: Reduce channel length 
B: Increase the thickness of gate oxide 
C:  Increase channel width
D: Reduce the doping concentration of substrate
答案: 【 Reduce the doping concentration of substrate】

2、判断题：
‍When MOSFET is in subthreshold region, the minority carrier concentration on the substrate surface is between intrinsic carrier concentration and substrate equilibrium majority carrier concentration.‌‍‌
选项：
A: 正确
B: 错误
答案: 【 正确】

4.5.1

1、单选题：
‎Which of the following measures can prevent the channel punch-through of MOSFET?‍‎‍
选项：
A: Reduce channel length 
B: Increase substrate doping concentration
C: Increase the thickness of gate oxide 
D: Increase channel width
答案: 【 Increase substrate doping concentration】

4.5.2

1、判断题：
‏When the temperature of n-channel MOSFET decreases, the threshold voltage of the device will increase. ‎
选项：
A: 正确
B: 错误
答案: 【 正确】

2、判断题：
‌When the gate voltage of MOSFET is large, the drain current will decrease with the increase of temperature.‍‌‍
选项：
A: 正确
B: 错误
答案: 【 正确】

4.6

1、多选题：
‎Which of the following measures can improve the transconductance of  MOSFET?‎‎‎
选项：
A: Reduce channel length 
B: Increase substrate doping concentration
C: Increase the thickness of gate oxide 
D: Increase the mobility of channel carrier 
答案: 【 Reduce channel length ;
Increase the mobility of channel carrier 】

2、判断题：
​The drain-source conductance of MOSFET is the slope of the output characteristic curve, and the transconductance is the slope of the transfer characteristic curve. ‏​‏
选项：
A: 正确
B: 错误
答案: 【 正确】

4.7.1

1、单选题：
Which of the following measures can alleviate the short channel effect of threshold voltage of MOSFET: (  )‌‌‌
选项：
A: Reduce substrate doping concentration
B: Reduce the channel length
C: Increase the junction depth of source and drain 
D: Reduce oxide thickness
答案: 【 Reduce oxide thickness】

2、判断题：
​When the channel width of MOSFET is very small, the threshold voltage will decrease with the increase of the channel width.‌​‌
选项：
A: 正确
B: 错误
答案: 【 正确】

4.7.2

1、多选题：
‎After velocity saturation occurs in the MOSFET, which of the following physical quantities will not be related to the channel length.‌‎‌
选项：
A: saturation drain-source voltage
B: transconductance
C: saturation drain current
D: threshold voltage
答案: 【 transconductance;
saturation drain current】

2、判断题：
‏MOSFET channel pinch off always occurs before speed saturation.‍‏‍
选项：
A: 正确
B: 错误
答案: 【 错误】

4.7.3

1、多选题：
‎‍What are the influnces of long time hot electric effect on the MOSFET performances ?‎‎‍‎
选项：
A: VT  increases with time
B: Transconductance gm increases