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Electronics Devices & Circuit Question List

Electronics Devices & Circuit Question List
Electronics Devices & Circuit Question List

Electronics Devices & Circuit Question List

Q. A p-n junction in series with a 100 ohms resistor is forward biased so that a current of 100 mA flows. If voltage across this combination is instantaneously reversed to 10 V at t=0, the reverse current that flows through the diode at t=0 is approximately through the diode at t=0 is approximately given by-

Ans. 100 mA

Q. The built-in potential in a p-n junction-

Ans. Is equal to the difference in the Fermi level of the sides expressed in volts

Q. The diffusion potential across a p-n junction-

Ans. Increases with increases in doping concentration

Q. A BJT is said to be operating in the saturation region if-

Ans. Both the junctions are forward biased.

Q. To obtain very high input and output impedance in a feedback amplifier, the topology mostly used is-

Ans. Current series

Q. A power amplifier delivers 50W output at 50% efficiency. The ambient temperature is 250 C.if maximum allowable junction temperature is 150 deg C then maximum thermal resistance that can be tolerated is-

Ans. 5deg C/W

Q. If a transistor with both of its junctions forward biased but with the collector base forward bias greater than the emitter base forward bias, then it is operating in the-

Ans. Reverse saturation mode

Q. The dissipation at the collector is zero in the quiescent state and increases with excitation he can a

Ans. Class B amplifier

Q. Avalanche photodiodes are preferred over PIN diodes in optical communication system because of-

Ans. Larger power handling capacity

Q. The given figure shows a silicon transistor connected as a common emitter amplifier. The quiescent collector voltage of the circuit is approximately-

Ans. 14V

Q. The transition region in an open circuits p-n junction contains-

Ans. Free electrons only

Q. In a p-n diode hole diffuse from p-region to n-region because-

Ans. Holes are urged to move by the barrier potential

Q. In a pn diode with the increases of reverse bias, the reverse current

Ans. Remains constant

Q. In silicon diode reverse saturation current I0 varies as-

Ans. T

Q. In an npn diffused junction transistor the p-type base reigns is formed on the n-type collector reigns through process of-

Ans. Epitaxial

Q. In a pnp transistor operating in the active regins; in the base reigns the main stream of current is-

Ans. Drift of holes

Q. In active reigns operation of a transistor-

Ans. Both junctions are forward biased

Q. In inverted operation of a transistor-

Ans. Both junctions are reverse biased

Q. Most of the small signal transistors are-

Ans. Npn germanium transistor in metallic case

Q. In a npn transistor operating in the active reigns the main current crossing the collector junctions from base side is-

Ans. Hole drift current

Q. A transistor with emitter junction forward biased and collector junction reverse biased is said to operate in-

Ans. Active reigns

Q. In a transistor current ICBO flow in-

Ans. Collector and emitter leads

Q. Use of buried layer in npn monolithic transistor causes the series resistor to-

Ans. Remain unaltered

Q. In comparison with conventional npn IC transistor the current gins of lateral pnp IC transistor is-

Ans. Lower

Q. An single IC chip contains more than 120 logic gates. This forms a case of-

Ans. VLSI

Q. The photoetching process consists in-

Ans. Diffusing impurities

Q. Reliability of IC’s may be increased by-

Ans. Operation at higher voltage

Q. Diffusion constant D of phosphorus impurity in silicon-

Ans. Continuously increases with increases of temperature

Q. Microwave IC’s-

Ans. Can be made using thin film on ceramics

Q. A diffused resistor in an IC-

Ans. Is fabricated after transistors diffusion

Q. Photo masking process in IC fabrication-

Ans. Is used to remove selected regions of SiO2

Q. Microwave IC’s-

Ans. Are initially being made as hybrid type on ceramic substrates

Q. Small size and weight IC’s-

Ans. Is a disadvantage in circuit operation

Q. Monolithic IC design is based on-

Ans. Extensive use of RC coupling

Q. The most important reason for of IC arrays is-

Ans. High reliability

Q. IC’s are economical for use in logic systems because-

Ans. Binary circuits are possible only with IC’s

Q. In processing IC slices-

Ans. Slices are never oxidized

Q. In IC’s diodes-

Ans. Are formed simultaneously with other elements

Q. An important merit of monolithic IC’s for linear applications Is that-

Ans. A wider frequency range is possible

Q. Solid state diffusion-

Ans. Can be carried out at low temperature

Q. The most important factor governing the cost of IC components is-

Ans. Area occupied by the component

Q. In silicon monolithic IC, isolation-

Ans. Can be obtained by use of SiO2 layer

Q. IC’s are probe tested-

Ans. On the complete slice for dc operation

Q. Extremely low power dissipation and low cost per gate can be achieved in which of the following IC?

Ans. TTL

Q. Which of the following digital IC family can give maximum fan out?

Ans. HTL

Q. In monolithic IC’s resistors are formed-

Ans. From manganic wire

Q. The term medium scale integration refers to IC’s-

Ans. with complexity below 10 gates

Q. in IC electronic system-

Ans. total system is same irrespective of type mounted as printed circuit board

Q. As complexity of a packaged IC is increased-

Ans. Overall cost always increases with the increases of complexity

Q. Large scale integration-

Ans. Refers only to integrated electronic components fabricated on full slices of silicon

Q. Very large scale integration(VLSI)-

Ans. Can not be applied to MOS types

Q. When a chip with more than two gates is assemble into an IC package then-

Ans. System becomes costlier

Q. In temperature control system IC’s-

Ans. Are used instead of thermo-couples

Q. In industrial electronic control-

Ans. We are simply concerned in establishing stable control with constant load conditions

Q. IC video amplifiers-

Ans. Give uniform amplification from dc upto typically 40 MHz

Q. A typical medium gain IC Op Amp-

Ans. Is suitable for use at low frequencies only

Q. An IC sense amplifier-

Ans. Is a memory system

Q. The most popularly used logic IC’s are-

Ans. TTL and DTL

Q. A dual 4 input gates IC consists of-

Ans. Four gates each with two inputs

Q. In a multiphase IC isolation is obtained by-

Ans. Un-doped silicon

Q. IC’s use silicon primarily because-

Ans. Of its higher forbidden energy gap

Q. In order to form a structure containing both pnp and npn transistors monolithic IC require-

Ans. Three layers

Q. Transistors in monolithic IC’s-

Ans. Use isolation junction as the collector junction

Q. In a JFET beyond the pinch off voltage as drain voltage increases; the drain current-

Ans. May increases or decreases

Q. N-channel FETs are superior t p-channel FETs because-

Ans. They have lower pinch off voltage

Q. When hats to source voltage VGS of a p-channel JEFT is mode more positive the drain current-

Ans. May increases or decreases

Q. The main drawback of a JEFT is its-

Ans. higher noise

Q. out of the devices mentioned below the fastest switching devices is-

Ans. JFED

Q. JFED can operate in-

Ans. Both depletion and enhancement modes simultaneously

Q. Which of the following device has the highest input impedance?

Ans. MOSFET

Q. A field effect transistor (FET)-

Ans. Uses a forward biased junction

Q. The operation of a JFET involves-

Ans. Flow of minority carriers alone

Q. A pnpn diode is a-

Ans. Voltage controllable device

Q. The pnpn diode-

Ans. May function either as a unilateral or as a bilateral device

Q. After firing an SCR if gats pulse is removed then SCR current-

Ans. rises up

Q. An SCR is a-

Ans. Pnpn diode with three terminals

Q. Triac is a-

Ans. 2 terminals bidirectional switch

Q. Diac is a-

Ans. 2 terminals bidirectional switch

Q. Diac is a silicon device with-

Ans. 4 layers and no gate

Q. Thermistor is used measurement of power at-

Ans. Very high

Q. In a photodiode light is focused is of the order of-

Ans. 1 ns

Q. In phototransistor light is focused to fall on-

Ans. All the three region of the transistor

Q. Photovoltaic emf of a Ge photovoltaic cell is of the order of-

Ans. volt

Q. photovoltaic emf of a Si photovoltaic cell is of the order of-

Ans. 1.1 volt

Q. Conversion efficiency of a silicon solar cell is about-

Ans. 14%

Q. LED gives off visible light from-

Ans. P region alone

Q. LEDs fabricated from Ga As emit radiation in the-

Ans. Visible range

Q. In a tunnel diode impurity concentration is of the order of-

Ans. 1 in 103

Q. In a tunnel diode depletion layer width is of the order of-

Ans. micron

Q. tunnel diode-

Ans. has a small hole in its center permitting tunneling

Q. tunnel diode is a pn diode with-

Ans. very high doping in n region

Q. the most important application of tunnel diode is as-

Ans. rectifier

Q. Avalanche break down results basically du to-

Ans. Emission of electrons

Q. Avalanche breakdown results at applied-

Ans. Forward bias below 6 volts

Q. Zener breakdown results basically due to-

Ans. High thermal energy of the electrons

Q. Zener breakdwon results at applied-

Ans. reverse bias below 6 volt

Q. on increasing the current through the zener diode by a factor of 2, the voltage across the diode-

Ans. remains almost uncharged

Q. the dynamic resistance of a zener diode-

Ans. decreases with increases of its current

Q. zener breakdown diode have breakdown voltage which?

Ans. Has negative temperature coefficient

Q. Avalanche breakdown diode have breakdown voltage-

Ans. Independent of temperature

Q. A bilateral pnpn diode switch-

Ans. Consistor of two pnpn diode in parallel but in opposite order

Q. A semiconductor photo-diode uses-

Ans. Photo-emissive effect

Q. LEDs have response time of the order of-

Ans. ns

Q. In LED when excited electrons revert from conduction band to valence band the phenomenon utilized is-

Ans. Energy transfer from one electron to other

Q. The temperature coefficient of breakdown diode is defined s of-

Ans. Breakdown voltage with temperature

Q. An infra-red LED IS usually fabricated from-

Ans. Ga As P.

Q. A zener diode works on the principle of-

Ans. Diffusion of charge carriers across the junctions

Q. The p-type substrate in a conventional pn junction isoated integrated circuit should be connected to-

Ans. Most negative potential available in the circuit

Q. A long specimen of p-type semiconductor material-

Ans. Is electrically neutral

Q. Silicon diode is less suited for low voltage rectifier operation because-

Ans. Its break down voltage is high

Q. The transition region in an open circuited p-n junction contains-

Ans. Free electrons only

Q. In a p-n diode hole diffuse from p-region to n-region because-

Ans. Holes are urged to move by the barrier potential

Q. In an unbiased p-n junction the junction current at equilibrium is-

Ans. Zero because no charges cross the junction

Q. In an unbiased pn junction zero current implies that-

Ans. Number of holes diffusing from p- side to n-side equals the number of electrons diffusing from n-side to p-side

Q. A reverse based pn junction has-

Ans. Extremely small constant reverse current

Q. In a silicon diode the reverse saturation current is of the order of-

Ans. 1nA

Q. In Ge diode the cut in voltage is about-

Ans. 0.6V

Q. The reverse bias on pn junctions-

Ans. Increases the reverse current

Q. In a formed biased pn diode-

Ans. Forward current Is zero

Q. In a pnp transistor operating in the active region the concentration of minority carrier holes in the n-region at collector junction Jc is-

Ans. Thermal equilibrium value Pno of emitter

Analog Circuit Technical Question & Answer

Q. in a pnp Ge transistor the cut in voltage is about-

Ans. -0.5V

Q. In a pnp Si transistor the cut in voltage is about-

Ans. -0.5V

Q. For active region operation of a pnp transistor-

Ans. Emitter is negative with respect to base

Q. For active region operation of npn transistor-

Ans. Base is at the same voltage as collector

Q. MOS transistor-

Ans. Has only two electrodes

Q. Power transistors are invariably provided with-

Ans. Soldered connections

Q. Heat sink removes heat from a power transistor mainly by-

Ans. Conduction

Q. In an npn transistor the function of emitter is-

Ans. To inject electrons into the collector

Q. A single monolithic IC chip occupies area of about-

Ans. 200 mil2

Q. Monolithic IC chip has thickness o about-

Ans. 5 mils

Q. Silicon dioxide layer is used in IC chips for-

Ans. Diffusing elements

Q. Substrate in a monolithic IC has thickness of the order of-

Ans. 5mils

Q. A multichip circuit-

Ans. Consists of number of interconnected thin film circuit

Q. Main advantage of IC technology is possibility of-

Ans. Using high values of capacitors

Q. Capacitors of integrated circuit-

Ans. Are always of very high values

Q. Overall cost of an IC-

Ans. Is in general lower than the corresponding discrete component assembly

Q. Cost of monolithic IC is-

Ans. Increases with increase of quantity produced

Q. Digital IC’s are mainly designed for use as-

Ans. Logic system in digital computers

Q. Application of IC’s industrial control-

Ans. Is being successfully used

Q. Use of IC’s in measuring instruments-

Ans. Requires developments of special circuit

Q. In IC’s the main elements contributing to reduced reliability is-

Ans. Diffused resistors

Q. In IC technology main merit of MOS transistor structure is-

Ans. Lower parasitic capacitance

Q. The photo-resist process is used-

Ans. To prevent photo response

Q. Monolithic IC’s-

Ans. Are made using the diffused planar process

Q. Thick film components are formed-

Ans. With conducting ink and a glass metal slurry silk careened on a ceramic substrate

Q. Thin film passive elements-

Ans. Are formed by photo masking and diffusion

Q. Thin film technology-

Ans. Uses vapor deposition of material on a substrate

Q. The Two level system of inter-collection-

Ans. Must not allow interconnections on the two levels to cross each other-

Q. Large memory arrays-

Ans. Can not be formed using MOS technology

Q. An integrated electronic component is-

Ans. A discrete device assembly

Q. The dual-in-line package is usually assembled into printed circuit cards by-

Ans. Soldering each lead individually

Q. Advantage of the dual-in-line package is that it-

Ans. Is compatible with PCB assembly methods

Q. Liners MOS IC’s-

Ans. Are not possible

Q. IC’s ,made by sputtering material on a ceramic substrate are called-

Ans. Thick film IC’s

Q. In a combined gate monolithic IC-

Ans. Total number of gates is generally below ten

Q. The material popularly used for contracts and interconnections in IC’s is-

Ans. Aluminium

Q. Transistor in monolithic IC’s-

Ans. Use isolation junction as the collector junction

Q. A diffused resistor in an Ic

Ans. Can be only of n-type

Q. MOS IC’s are being developed for-

Ans. Matrix switching arrays in telephone exchanges

Q. Pinch off voltage VP for an FET is the drain voltage at which?

Ans. Significant drain current starts flowing

Q. FET has offset voltage of about-

Ans. 0.6V

Q. The charge carriers in a p-channel FET are-

Ans. Electrons alone

Q. The charge carriers in an n-channel FET are-

Ans. Holes alone

Q. When the gate to source voltage VGS of an n-type channel JET is made more and more negative the drain current-

Ans. Decreases

Q. The magnitude of the threshold voltage Vt for enhancement MOSFET is of the order of-

Ans. 40V

Q. The input gate current of FET is-

Ans. Negligibly small

Q. Which of the following transistor is affected by static electricity?

Ans. JFET

Q. FET-

Ans. Uses a forward biased junction

Q. A pnpn device having no gate is called-

Ans. SCR

Q. A pnpn diode is a-

Ans. Voltage controllable device

Q. In pnpn diode breakover condition is marked by-

Ans. A sudden glow taking place

Q. Holding current in a pnpn diode is the-

Ans. Maximum operating current

Q. A pnpn diode-

Ans. Is always made of silicon

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