1. The impurity commonly used for realizing the base region of a silicon NPN transistor is

a. Gallium

b. Indium

c. Boron

d. Phosphorous

2. If for a silicon NPN transistor, the base to emitter voltage (V

a. Normal active mode

b. Saturation mode

c. Inverse active mode

d. Cutoff mode

3. Consider the following statements S

S

S

Which of the following is correct?

a. S

b. Both S

c. Both S

d. S

4. Assuming V

5. The given figure is the voltage transfer characteristic of

6. In abrupt PN junction, the doping concentrations on the P side and N side are N

a. 2.7 µm

b. 0.3 µm

c. 2.25 µm

d. 0.75 µm

7. The resistivity of a uniformly doped N type silicon sample is 0.5 Ω-cm. If the electron mobility (µ

a. 2 x 10

b. 1 x 10

c. 2.5 x 10

d. 2 x 10

8. Consider an abrupt PN junction. Let V

a. 4 pF

b. 2 pF

c. 0.25 pF

d. 0.75 pF

9. Consider the following statements S

S

S

Which of the following is correct?

a. S

b. Both S

c. S

d. Both S

10. The drain of an N channel MOSFET is shorted to the gate so that V

a. 2 mA

b. 3 mA

c. 9 mA

d. 4 mA

11. The longest wavelength that can be absorbed by silicon, which has the band gap of 1.12 eV is 1.1 µm. If the longest wavelength that can be absorbed by another material is 0.87 µm, then the band gap of this material is

a. 1.416 eV

b. 0.886 eV

c. 0.854 eV

d. 0.706 eV

12. The neutral base width of a bipolar transistor biased in the active region is 0.5 µm. The maximum electron concentration and the diffusion constant in the base are 10

a. 800 A/cm

b. 8 A/cm

c. 200 A/cm

d. 2 A/cm

13. Assuming that the β of the transistor is extremely large and V

14. In the voltage regulator shown, the load current can vary from 100 mA to 500 mA. Assuming that the zener diode is ideal (i.e. the zener knee current is negligibly small and zener resistance is zero in the breakdown region), the value of R is

a. Gallium

b. Indium

c. Boron

d. Phosphorous

**Solution :**https://www.youtube.com/watch?v=NkcGfnAzVvE2. If for a silicon NPN transistor, the base to emitter voltage (V

_{BE}) is 0.7 volts and collector to base voltage (V_{CB}) is 0.2 volts, then the transistor is operating in thea. Normal active mode

b. Saturation mode

c. Inverse active mode

d. Cutoff mode

**Solution :**https://www.youtube.com/watch?v=EWiTi5LriHE3. Consider the following statements S

_{1}and S_{2}.S

_{1}: the β of a BJT reduces if the base width is increasedS

_{2}: the β of a BJT increases if the doping concentration in the base is increasedWhich of the following is correct?

a. S

_{1}is FALSE and S_{2}is TRUEb. Both S

_{1}and S_{2}are TRUEc. Both S

_{1}and S_{2}are FALSEd. S

_{1}is TRUE and S_{2}is FALSE**Solution :**https://www.youtube.com/watch?v=91xuzfdvnqk4. Assuming V

_{CEsat}= 0.2 volts and β = 50, the minimum base current (I_{Bmin}) required to drive the transistor in figure to saturation is**Solution :**https://www.youtube.com/watch?v=OhDfZeDskwo

5. The given figure is the voltage transfer characteristic of

**Solution :**https://www.youtube.com/watch?v=lPY4XzAWeSg6. In abrupt PN junction, the doping concentrations on the P side and N side are N

_{A}= 9 x 10^{16}cm^{-3}and N_{D}= 1 x 10^{16}cm^{-3}respectively. The PN junction is reverse biased and the total depletion width is 3 µm. The depletion width on the P side isa. 2.7 µm

b. 0.3 µm

c. 2.25 µm

d. 0.75 µm

**Solution :**https://www.youtube.com/watch?v=XyzrofQ1DsI7. The resistivity of a uniformly doped N type silicon sample is 0.5 Ω-cm. If the electron mobility (µ

_{n}) is 1250 cm^{2}/V-sec and the charge of an electron is 1.6 x 10^{-19}coulomb, then the donor impurity concentration (N_{D}) in the sample isa. 2 x 10

^{16}/ cm^{3}b. 1 x 10

^{16}/ cm^{3}c. 2.5 x 10

^{15}/ cm^{3}d. 2 x 10

^{15}/ cm^{3}**Solution :**https://www.youtube.com/watch?v=_bfVDPlUFWw8. Consider an abrupt PN junction. Let V

_{bi}be the built in potential of this junction and V_{R}be the applied reverse bias. If the junction capacitance (C_{J}) is 1 pF for V_{bi}+ V_{R}= 1 volt, then for V_{bi}+ V_{R}= 4 volts, the value of C_{J}will bea. 4 pF

b. 2 pF

c. 0.25 pF

d. 0.75 pF

**Solution :**https://www.youtube.com/watch?v=3jTOs2F7oHA9. Consider the following statements S

_{1}and S_{2}.S

_{1}: the threshold voltage (V_{T}) of a MOS capacitor decreases with increase in gate oxide thicknessS

_{2}: the threshold voltage (V_{T}) of a MOS capacitor decreases with increase in substrate doping concentration.Which of the following is correct?

a. S

_{1}is FALSE and S_{2}is TRUEb. Both S

_{1}and S_{2}are TRUEc. S

_{1}is TRUE and S_{2}is FALSEd. Both S

_{1}and S_{2}are FALSE**Solution :**https://www.youtube.com/watch?v=jmKFRCr0xa010. The drain of an N channel MOSFET is shorted to the gate so that V

_{GS}= V_{DS}. The threshold voltage (V_{T}) of MOSFET is 1 volt. If the drain current (I_{D}) is 1 mA for V_{GS}= 2 volts, then for V_{GS}= 3 volts, I_{D}isa. 2 mA

b. 3 mA

c. 9 mA

d. 4 mA

**Solution :**https://www.youtube.com/watch?v=F1cZOGLgZIA11. The longest wavelength that can be absorbed by silicon, which has the band gap of 1.12 eV is 1.1 µm. If the longest wavelength that can be absorbed by another material is 0.87 µm, then the band gap of this material is

a. 1.416 eV

b. 0.886 eV

c. 0.854 eV

d. 0.706 eV

**Solution :**https://www.youtube.com/watch?v=wlIK6u3cSrE12. The neutral base width of a bipolar transistor biased in the active region is 0.5 µm. The maximum electron concentration and the diffusion constant in the base are 10

^{14}cm^{-3}and D_{n}= 25 cm^{2}/sec respectively. Assuming negligible recombination in the base, the collector current density isa. 800 A/cm

^{2}b. 8 A/cm

^{2}c. 200 A/cm

^{2}d. 2 A/cm

^{2}**Solution :**https://www.youtube.com/watch?v=y5ivXtuocFU13. Assuming that the β of the transistor is extremely large and V

_{BE}= 0.7 volts, I_{C}and V_{CE}in the circuit shown are**Solution :**https://www.youtube.com/watch?v=ETrg3InTVmY14. In the voltage regulator shown, the load current can vary from 100 mA to 500 mA. Assuming that the zener diode is ideal (i.e. the zener knee current is negligibly small and zener resistance is zero in the breakdown region), the value of R is

**Solution :**https://www.youtube.com/watch?v=ow6gYqOD3_w
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