1. PIN diode is a photosensitive diode because of _______
a) large current flow in p and n region
b) depletion layer increases giving a larger surface area
c) stronger covalent bonds
d) low carrier storage
Explanation: An intrinsic layer that is sandwiched between p and n layers. This gives a larger surface area making it compatible for photosensitivity. Reverse bias causes an increased depleted region in a PIN diode
2. During forward bias, the PIN diode acts as _______
a) a variable resistor
b) a variable capacitor
c) a switch
d) an LED
Explanation: In forward bias, the forward resistance decreases and acts as a variable resistor. The low frequency model of a PIN diode neglects the input capacitive values.
3. During reverse bias, the PIN diode acts as _______
a) Variable resistor
b) Switch
c) Variable capacitor
d) LED
Explanation: In reverse bias, the intrinsic layer is completely covered by depletion layer. The stored charges vanishes acting like a variable capacitor. The high frequency model of a PIN diode neglects the input resistances.
4. When the p and n regions are used for high resistivity, the depletion region at the respective places is called _________
a) Q and ϒ regions
b) ϒ and π regions
c) Q and π regions
d) π and ϒ regions
Explanation: When p region is used for high resistance, the depletion layer is high at p side.When n side is used the depletion layer is high at n side. They are called as π and ϒ regions respectively.
5. The applications for PIN diode are __________
a) Microwave switch
b) LED
c) Voltage regulator
d) Amplifier
Explanation: Being employed at 300Hz, the swept voltage is attained at π region.Then it’s used as a microwave switch. Swept voltage is nothing but, the voltage at which the complete intrinsic layer is swept out as a depleted one.
6. In high frequency model, the values of resistance ‘R’ and capacitance ‘C’ are _______
a) 0.1 to 10KΩ and 0.02 to 2pF respectively
b) 1 to 10KΩ and 0.02 to 2pF respectively
c) 10 to 100KΩ and 0.02 to 2pF respectively
d) 0.1 to 10KΩ and 2 to 20pF respectively
Explanation: At high frequency, the applied values for resistance and capacitance is 0.1 to 10KΩ and 0.02 to 2pF respectively. At high frequencies, it almost acts as a perfect resistor.
7. What happens in PIN diode for low frequency model?
a) reactance decreases
b) conductance increases
c) resistance increases
d) reactance increases
Explanation: In a low frequency model, the resistance decreases and reactance increases.Here the variable resistance is neglected. At low frequencies, the charge can be removed and the diode can be turned off.
8. Which of the following is true about a PIN diode?
a) it’s photosensitive in reverse bias
b) it offers low resistance and low capacitance
c) it has a decreased reversed breakdown voltage
d) carrier storage is low
Explanation: Due to increased depletion region, the covalent bonds break and increase the surface area for photosensitivity. This property is used in fields of light sensors, image scanners, artificial retina systems
9. In the application of frequency models, the value of forward current is _____
a) IF = A(µPP + µNN)q
b) IF = A(µPN + µNP)q
c) IF = A(µPP – µNN)q
d) IF = A(µPN – µNP)q
Explanation: The forward current depends on mobility and carrier concentration. In frequency models, the value of forward current is IF = A*(µPP + µNN)q. Where, µP and µN are the mobility of p and n type charge carriers respectively.
10. The forward resistance for a PIN diode is given by ________
a) RF = W/σP
b) RF = W/σN
c) RF = WσP
d) RF = WσN
Explanation: Forward resistance for a PIN diode depends on the width, current density and positive carrier concentration of the diode. No diode is perfectly ideal. In practise, a diode offers a small resistance in forward bias which is called as forward resistance.