Gate 2019: Electronic Devices and Circuits Quiz 8

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Question 1

The bandwidth of a single tuned amplifier is 20 kHz. If 5 such stages are cascaded, what will be the total bandwidth of the multi-stage amplifier?

• A100 kHz
• B7.71 kHz
• C125.25 kHz
• D15.42 kHz

Question 2

In Avalanche photo diode assume the saturation velocity of the charge carriers generated by impact ionization by photon absorbtion be equal to 10⁷ cm/sec in a depletion region that is 10m wider then the transition time will be

• A1 psec
• B100 psec
• C10 psec
• D10¹¹ sec

Question 3

The transistor in the circuit shown below has the parameter mA/V². V_T = -2 V, drain current = 0.5 mA.(neglect channel length modulation)

The value of C_C such that the lower 3 dB frequency is 20 Hz is

• A
• B
• C
• D

Question 4

The resistance of a si sample with cross-section of 2 cm² and a length of 2 m with the doping impurity of phosphorus and boron concentration of 10¹⁸ cm^-3 and 210¹⁵ cm^-3 respectively is kept at 300⁰K will be equal to
(Assuming _n= 1300 cm²/v-sec)

• A4.8
• B0.048
• C0.48
• D5.3

Question 5

A silicon wafer has 100 nm of oxide on it and is inserted in a furnace at a temperature above 1000ºC for further oxidation in dry oxygen. The oxidation rate

• AIs independent of current oxide thickness and temperature
• BIs independent of current oxide thickness but depends on temperature
• CSlows down as the oxide grows
• DIs zero as the existing oxide prevents further oxidation

Question 6

Which of the following is true?

• AA silicon wafer heavily doped with boron is a p⁺ substrate
• BA silicon wafer lightly doped with boron is a p⁺ substrate
• CA silicon wafer heavily doped with arsenic is a p⁺ substrate
• DA silicon wafer lightly doped with arsenic is a p⁺ substrate

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