GATE EC : Electronic Devices & Circuits - National Champion Test for ESE & GATE EC Exams

Question 1

An n-type silicon sample is uniformly illuminated with light which generates 10²⁰ electron hole pairs per cm³ second. The minority carrier lifetime in the sample is 1 μs. In the steady state, the hole concentration in the sample is approximately 10^x, where x is an integer. The value of x is___

Question 2

Which of the following option will provide the least resistance across the bulb?

Question 3

Two resistance R₁ and R₂ give combined resistance of 4.5 ohms when in series and 1 ohm when in parallel. The resistance are

Question 4

Thin gate oxide in a CMOS process in preferably grown using

Question 5

What is the output waveform V₀ for a sinusoidal input of peak-peak amplitude of 4V. Assume that Z1 and Z2 are two identical Zener diodes of 4.7V, and R1=10kohm and R2=20kohm.

Question 6

How could Schrodinger’s equation be relevant in the practical design of a Cathode- Ray Tube?

Question 7

The power rating of a 470 ohm resistor carrying a current of 40mA should be

Question 8

In the circuit shown, assume that diodes D₁ and D₂ are ideal. In the steady state condition, the average voltage V_ab (in Volts) across the 0.5 μF capacitor is _______.
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Question 9

For a particular toroidal inductor core, the inductance value obtained for 50 Turns is 200μH. If two such inductors are wired in parallel, the resulting inductance is

Question 10

Assuming V_CEsat = 0.2 V and β = 50, the minimum base current (I_B) required to drive the transistor in figure to saturation is?

Question 11

In the circuit shown below, the Zener diode is ideal and the Zener voltage is 6V. The output voltage V₀ (in volts) is ____________.
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Question 12

An n-type silicon bar 0.1 cm long and µm³ in the cross-sectional area has a majority carrier concentration of 5 × 10²⁰/m³ and the carrier mobility is 0.13 m²/V–s at 300 K. If the charge of an electron is 1.6 × 10^–19 coulomb, if the area of the bar is (Area = 100 * 10^-12) then the resistance of the bar is

Question 13

The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: T = 300K, electronic charge =1.6 × 10^–19C, thermal voltage = 26mV and electron mobility = 1350cm²/V–s

The magnitude of the electric field at x = 0.5 μm is

Question 14

If C denotes the counterclockwise unit circle, the value of the contour integral $Description: Description: D:\GradeStack Courses\GATE Tests (Sent by Ravi)\GATE EC 10-Mar\GATE-ECE-2015-Paper-2_files\image323.png$ is ______

Question 15

The action of a JFET in its equivalent circuit can best be represented as a

Question 16

What is the output voltage across the 900 ohm load in the circuit given below?

Question 17

Which one of the following is the lowest level of abstraction for representation of a digital system?

Question 18

A coaxial capacitor of inner radius 1 mm and outer radius 5 mm has a capacitance per unit length of 172 pF/m. If the ratio of outer radius to inner radius is doubled, the capacitance per unit length (in pF/m) is ___.

Question 19

A MOS capacitor made using p type substrate is in the accumulation mode. The dominant charge in the channel is due to the presence of

Question 20

The magnitude of the electron drifts current density at
x = 0.5 μm is

Question 21

A square pulse of 3 volts amplitude is applied to C-R circuit shown in figure. The capacitor is initially uncharged. The output voltage v₀ at time t = 2 sec is

Question 22

In the circuit shown in the figure, the BJT has a current gain (β) of 50. For an emitter-base voltage V_EB = 600 mV, the emitter-collector voltage V_EC (in Volts) is _____.
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Question 23

If the base width in a bipolar junction transistor is doubled, which one of the following statements will be TURE?

Question 24

The desirable properties of transformer core material are

Question 25

The transistors used in a portion of the TTL gate shown in figure have β =100. The base-emitter voltage of is 0.7V for a transistor in active region and 0.75V for a transistor in saturation. If the sink current I =1mA and the output is at logic 0, then the current I_R will be equal to
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Question 26

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 10¹⁴/cm³ and D_n = 25 cm²/sec respectively. Assuming negligible recombination I the base, the collector current density is (the electron charge is 1.6 × 10^–19 coulomb)

Question 27

In a uniformly doped BJT, assume that N_E, N_B and N_C are the emitter, base and collector dopings in atoms/cm³, respectively. If the emitter injection efficiency of the BJT is close unity, which one of the following conditions is TRUE?

Question 28

For the BJT Q₁ in the circuit shown below, β = ∞, V_BEon = 0.7 V, V_CEsat = 0.7 V. The switch is initially closed. At time t = 0, the switch is opened. The time t at which Q₁ leaves the active region is

Question 29

For an npn transistor connected as shown in figure, V_BE = 0.7 Volts. Given that reverse saturation current of the junction at room temperature 300 °K is 10^-13 A, the emitter current is

Question 30

The source of a silicon (n_i = 10¹⁰ per cm³) n-channel MOS transistor has an area of 1 sq μm and a depth of 1 μm. If the dopant density in the source is 10¹⁹/cm³, the number of holes in the source region with the above volume is approximately