ECE Paper - 3

May 30th, 2007 | GATE

1. The minimum number of 2-to -1 multiplexers required to realize a 4-to 1 multiplexer is

A. 1
B. 2
C. 3
D. 4
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2. It is desired to multiply the numbers 0AH by 0BH and store the result in the accumulator. The numbers are available in registers B and C respectively. A Part of the 8085 program for this purpose is given below:
MVI A, 00H
Loop;- - - - - - - - -
——————–
——————-
HLT END
The sequence of instruction to the complete the program would be

A. JNZ LOOP, ADD B, DCR C
B. ADD S, JNZ LOOP, DCR C
C. DCR C, JNZ LOOP, ADD B
D. ADD B, DCR C, JNZ LOOP
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3. Let x(n) = ( 1/2)^n u(n), y(n)=x^2(n) and Y(e^jw) be the Fourier transform of y(n). Then Y(e^j0) is

A. 1/4
B. 2
C. 4
D. 4/3
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4. Consider a lossless antenna with a directive gain of +6dB. If 1 mW of power is fed to it the total power radiated by the antenna will be

A. 4 mW
B. 1 mW
C.7 mW
D. 1/4 mW
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5. In an abrupt p-n junction, the doping concentrations on the p-side and n-side are NA = 9x 10^16/cm^3 and ND = 1 x 10^16/cm^3 respectively. The p-n junction is reverse biased and the total depletion width is 3 micro-m. The depletion width on the p-side is

A. 2.7 micro-m
B. 0.3 micro-m
C. 2.25 micro-m
D. 0.75 micro-m
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6. Consider a lossless antenna with a directive gain of +6dB. If 1 mW of power is fed to it the total power radiated by the antenna will be

A. 4 mW
B. 1 mW
C. 7 mW
D. 1/4 mW
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7. An AM signal is detected using an envelope detector The carrier frequency and modulating signal frequency are 1 MHz and 2 kHz respectively. An appropriate value for the time constant of the envelope detector is

A. 500 msec
B. 20 msec
C. 0.2 msec
D. 1 msec
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8. The phase velocity of an electromagnetic wave propagating in a hollow metallic rectangular waveguide in the TE10 mode is

A. equal to its group velocity
B. less than the velocity of light in free space
C. equal to the velocity of light in free space
D. greater than the velocity of light in free space
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9. A low pass signal of 3 KHz bandwidth and amplitude over -5V to +5V range is sampled at Nyquist rate and converted to 8-bit PCM using uniform quantization. The mean squared value of message signal is 2 volts-squared. The SQNR in dB is:

A. 30.72 dB
B. 41.96 dB
C. 67.475 dB
D. None
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10. With an increase in temperature, the Fermi level in an instrinsic semiconductor

A. moves closer to the conduction band edge
B. moves closer to the valance band edge
C. moves into the conduction band
D. remains at the center of the forbidden gap
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11. A Boolean function f of two variables x and y is defined as follows:
f(0,0) = f(0,1) = f(1, 1) = 1; f(1,0) = 0
Assuming complements of x and y are not available, a minimum cost solution for realizing fusing only 2-input NOR gates and 2-input OR gates (each having unit cost) would have a total cost of

A. 1 unit
B. 4 unit
C. 3 unit
D. 2 unit
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12. Choose the function f(t); -infinity < t < infinity, for which a Fourier series cannot be defined.

A. 3 sin (25 t)
B. 4 cos (20 t + 3) + 2 sin (710 t)
C. exp(-|t| )sin(25t)
D. 1
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13. For the polynomial P(s) = s^5 + s^4 + 2*s^3 + 2*s^2 + 3*s + 15, the number of roots which lie in the right half of the s-plane is

A. 4
B. 2
C. 3
D. 1
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14. The bandgap of Silicon at room temperature is

A. 1.3 eV
B. 0.7 eV
C. 1.1 eV
D. 1.4 eV
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15. A system has poles at 0.01 Hz, 1 Hz and 80 Hz; zeros at 5 Hz, 100 Hz and 200 Hz. The approximate phase of the system-response at 20 Hz is

A. - 90°
B. 0°
C. 90°
D. - 180°
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16. 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

A. holes
B. electrons
C. positively charged ions
D. negatively charged ions
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17. Despite the presence of negative feedback, control system still have problems of instability because the

A. components used have nonlinearities.
B. dynamic equations of the subsystems are not known exactly.
C. mathematical analysis involves approximations.
D. system has large negative phase angle at high frequencies.
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18. The Fourier transform of a conjugate symmetric function is always

A. imaginary
B. conjugate anti-symmetric
C. real
D. conjugate symmetric
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19. A random variable X with uniform density in the interval 0 to 1 is quantized as follows:
If 0 <= X <= 0.3, xq = 0
If 0.3 <= X <= 1, xq = 0.7
where xq is the quantized value of X.
The root-mean square value of the quantization noise is

A. 0.573
B. 0.198
C. 2.205
D. 0.266
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20. Choose the correct one from among the alternatives A, B, C, D after matching an item from Group 1 with the most appropriate item in Group 2.

A. 1-T, 2-P, 3-U, 4-S
B. 1-S, 2-U, 3-P, 4-T
C. 1-S, 2-P, 3-U, 4-Q
D. 1-U, 2-R, 3-S, 4-Q
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