Tiêu đề SEMICONDUCTOR ELECTRONICS.docx.pdf ✅

14.SEMICONDUCTOR ELECTRONICS: MATERIALS,DEVIES AND SIMPLE CIRCUITS Single Correct Answer Type 1. In the following circuit, the output Y for all possible inputs A and B is expressed by the truth table ABY a) |0 0 0 0 1 0 1 0 0 1b) |0 0 1 0 1 1 1 0 1 1c) |0 0 1 0 1 0 1 0 0 1d) |0 0 0 0 1 1 1 0 1 2. Which is the correct diagram of a half-wave rectifier? a) b) c) d) 3. The following figure shows a logic gate circuit with two inputs A and B and the output C. The voltage waveforms of A, B and C are as shown below The logic circuit gate is a) AND gate b) NAND gate c) NOR gate d) OR gate 4. When the forward bias voltage of a diode is changed from 0.6 V to 0.7 V, the current changes from 5 mA to 15 mA. Then its forward bias resistance is a) 0.01 Ω b) 0.1 Ω c) 10 Ω d) 100 Ω 5. In extrinsic P and N-type semiconductor materials, the ratio of the impurity atoms to the pure semiconductor atoms is about a) 1 b) 10 −1 c) 10 −4 d) 10 −7 6. In the following, which one of the diodes is reverse biased? a) b) c) d) Page| 1

a) Zero b) 0.01 c) 0.02 d) 0.03 15. The potential in depletion layer is due to a) Electrons b) Holes c) Ions d) Forbidden band 16. Pure Si at 500 K has equal number of electron (n and hole concentrations of . Doping e ) (n h ) 1. 5×10 16 m −3 by indium increases n to . The doped semiconductor is of h 4. 5×10 22 m −3 a) n −type with electron concentration n e = 2. 5×10 23 m −3 b) p −type having electron concentration n e = 5×10 9 m −3 c) n −type with electron concentration n e = 5×10 22 m −3 d) p −type with electron concentration n e = 2. 5×10 10 m −3 17. A p-nphotodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly a) 10×10 Hz 14 b) 5×10 Hz 14 c) 1×10 Hz 14 d) 20×10 Hz 14 18. In an intrinsic semiconductor, the Fermi level is a) Nearer to valency band than conduction band b) Equidistance from conduction band and valency band c) Nearer to conduction band than valency band d) Bisecting the conduction band 19. A common emitter amplifier is designed with NPN transistor (α = 0. 99). The input impedance is 1 KΩ and load is 10 KΩ. The voltage gain will be a) 9.9 b) 99 c) 990 d) 9900 20. Find V AB a) 10 V b) 20 V c) 30 V d) None of these 21. In a transistor the collector current is always less than the emitter current because a) Collector side is reverse biased and the emitter side is forward biased b) A few electrons are lost in the base and only remaining ones reach the collector c) Collector being reverse biased, attracts less electrons d) Collector side is forward biased and the emitter side is reverse biased 22. A NPN transistor conducts when a) Both collector and emitter are positive with respect to the base Page| 3