GATE 2003 ECE Question Paper

2. A source of angular frequency 1 rad/sec has a source impedance consisting of 1Ω
resistance in series with 1 H inductance. The load that will obtain the maximum
power transfer is
(a) 1 Ω resistance
(b) 1 Ω resistance in parallel with 1 H inductance
(c) 1 Ω resistance in series with 1 F capacitor
(d) 1 Ω resistance in parallel with 1 F capacitor

3. A series RLC circuit has a resonance frequency of 1 kHz and a quality factor Q =
100. If each R, L and C is doubled from its original value, the new Q of the circuit
is
(a) 25 (b) 50 (c) 100 (d) 200

6. n-type silicon is obtained by doping silicon with
(a) Germanium (b) Aluminum (c) Boron (d) Phosphorus

7. The bandgap of silicon at 300 K is
(a) 1.36 eV (b) 1.10 eV (c) 0.80 eV (d) 0.67 eV

9. Choose proper substitutes for X and Y to make the following statement correct
Tunnel diode and Avalanche photodiode are operated in X bias and Y bias
respectively.
(a) X: reverse, Y: reverse (b) X: reverse, Y: forward
(c) X: forward, Y: reverse (d) X: forward, Y: forward

10. For an n-channel enhancement type MOSFET, if the source is connected at a
higher potential than that of the bulk (i.e. VSB > 0), the threshold voltage VT of
the MOSFET will
(a) remain unchanged (b) decrease
(c) change polarity (d) increase

11. Choose the correct match for input resistance of various amplifier configurations
shown below.

Configuration Input resistance
CB: Common Base LO: Low
CC: Common Collector MO: Moderate
CE: Common Emitter HI: High
(a) CB-LO, CC-MO, CE-HI (b) CB-LO, CC-HI, CE-MO
(c) CB-MO, CC-HI, CE-LO (d) CB-HI, CC-LO, CE-MO

14. If the differential voltage gain and the common mode voltage gain of a
differential amplifier are 48 dB and 2 dB respectively, then its common mode
rejection ratio is
(a) 23 dB (b) 25 dB (c) 46 dB (d) 50 dB

15. Generally, the gain of a transistor amplifier falls at high frequencies due to the
(a) internal capacitances of the device
(b) coupling capacitor at the input
(c) skin effect
(d) coupling capacitor at the output

16. The number of distinct Boolean expression of 4 variables is
(a) 16 (b) 256 (c) 1024 (d) 65536

17. The minimum number of comparators required to build an 8 it flash ADC is
(a) 8 (b) 63 (c) 255 (d) 256

18. The output of the 74 series of TTL gates is taken from a BJT in
(a) totem pole and common collector configuration
(b) either totem pole or open collector configuration
(c) common base configuration
(d) common collector configuration

19. Without any additional circuitry, an 8:1 MUX can be used to obtain
(a) some but not all Boolean functions of 3 variables
(b) all function of 3 variables but none of 4 variables
(c) all functions of 3 variables and some but not all of 4 variables
(d) all functions of 4 variables

20. A 0 to 6 counter consists of 3 flip flops and a combination circuit of 2 input
gate(s). The combination circuit consists of
(a) one AND gate (b) one OR gate
(c) one AND gate and one OR gate (d) two AND gates

25. A PD controller is used to compensate a system. Compared to the
uncompensated system, the compensated system has
(a) a higher type number (b) reduced damping
(c) higher noise amplification (d) larger transient overshoot

26. The input to a coherent detector is DSB-SC signal plus noise. The noise at the
detector output is
(a) the in-phase component (b) the quadrature-component
(c) zero (d) the envelope

27. The noise at the input to an ideal frequency detector is white. The detector is
operating above threshold. The power spectral density of the noise at the output
is
(a) raised cosine (b) flat (c) parabolic (d) Gaussian

28. At a given probability of error, binary coherent FSK is inferior to binary coherent
PSK by
(a) 6 dB (b) 3 dB (c) 2 dB (d) 0 dB

29. The unit of ∇ × H is
(a) Ampere (b) Ampere/meter
(c) Ampere/meter2
(d) Ampere-meter

30. The depth of penetration of electromagnetic wave in a medium having
conductivity σ at a frequency of 1 MHz is 25 cm. The depth of penetration at a
frequency of 4 MHz will be
(a) 6.25 cm (b) 12.50 cm (c) 50.00 cm (d) 100.00 cm

31. Twelve 1Ω resistances are used as edges to form a cube. The resistance between
two diagonally opposite corners of the cube is
(a)5/6Ω (b)1/6Ω (c) 6/5Ω (d)3/2Ω

40. Match items in Group 1 with items in Group 2, most suitably.

Group 1 Group 2
P LED 1 Heavy doping
Q Avalanche photodiode 2 Coherent radiation
R Tunnel diode 3 Spontaneous emission
S LASER 4 Current gain
(a) P – 1 Q – 2 R – 4 S - 3 (b) P – 2 Q – 3 R – 1 S - 4
(c) P – 3 Q – 4 R – 1 S - 2 (d) P – 2 Q – 1 R – 4 S - 3

41. At 300 K, for a diode current of 1 mA, a certain germanium diode requires a
forward bias of 0.1435V, whereas a certain silicon diode requires a forward bias
of 0.718V. Under the conditions stated above, the closest approximation of the
ratio of reverse saturation current in germanium diode to that in silicon diode is
(a) 1 (b) 5 (c) 4 × 10000 (d) 8 × 10000

43. When the gate-to-source voltage (VGS) of a MOSFET with threshold voltage of
400mV, working in saturation is 900 mV, the drain current in observed to be 1
mA. Neglecting the channel width modulation effect and assuming that the
MOSFET is operating at saturation, the drain current for an applied VGS of 1400
mV is
(a) 0.5 mA (b) 2.0 mA (c) 3.5 mA (d) 4.0 mA

44. If P is Passivation, Q is n-well implant, R is metallization and S is soruce/drain diffusion, then the order in which they are carried out in a standard n-well CMOS fabrication process, is
(a) P-Q-R-S (b) Q-S-R-P (c) R-P-S-Q (d) S-R-Q-P

45. An amplifier without feedback has a voltage gain of 50, input resistance of 1 KΩ
and output resistance of 2.5 KΩ. The input resistance of the current-shunt
negative feedback amplifier using the above amplifier with a feedback factor of
0.2, is
(a) 1/11KΩ (b)1/5KΩ (c) 5 KΩ (d) 11 KΩ

49. The action of a JFET in its equivalent circuit can best be represented as a
(a) Current Controlled Current Source
(b) Current Controlled Voltage Source
(c) Voltage Controlled Voltage Source
(d) Voltage Controlled Current Source

51. Three identical amplifiers with each one having a voltage gain of 50, input
resistance of 1 KΩ and output resistance of 250Ω, are cascaded. The open circuit
voltage gain of the combined amplifier is
(a) 49 dB (b) 51 dB (c) 98 dB (d) 102 dB

52. An ideal sawtooth voltage waveform of frequency 500 Hz and amplitude 3V is
generated by charging a capacitor of 2 µF in every cycle. The charging requires
(a) constant voltage source of 3 V for 1 ms
(b) constant voltage source of 3 V for 2 ms
(c) constant current source of 3 mA for 1 ms
(d) constant current source of 3 mA for 2 ms

55. A 4 bit ripple counter and a 4 bit synchronous counter are made using flip-flops
having a propagation delay of 10 ns each. If the worst case delay in the ripple
counter and the synchronous counter be R and S respectively, then
(a) R = 10 ns, S = 40 ns (b) R = 40 ns, S = 10 ns
(c) R = 10 ns, S = 30 ns (d) R = 30 ns, S = 10 ns

60. In an 8085 microprocessor, the instruction CMP B has been executed while the
content of the accumulator is less than that of register B. As a result
(a) Carry flag will be set but Zero flag will be reset
(b) Carry flag will be reset but Zero flag will be set
(c) Both Carry flag and Zero flag will be reset
(d) Both Carry flag and Zero flag will be set

61. Let X and Y be two statistically independent random variables uniformly
distributed in the ranges (-1,1) and (-2,1) respectively. Let Z = X + Y. then the
probability that [Z≤-2] is
(a) zero (b)1/6 (c)1/3 (d)1/12

81. The input to a linear delta modulator having a step-size = 0.628 is a sine wave with frequency fm and peak amplitude Em. If the sampling frequency fs = 40 kHz,
the combination of the sine-wave frequency and the peak amplitude, where slope
overload will take place is
Em fm
(a) 0.3 V 8 kHz
(b) 1.5 V 4 kHz
(c) 1.5 V 2 kHz
(d) 3.0 V 1 kHz

82. If S represents the carrier synchronization at the receiver and ρ represents the bandwidth efficiency, then the correct statement for the coherent binary PSK is
(a) ρ = 0.5, S is required (b) ρ = 1.0, S is required
(c) ρ = 0.5, S is not required (d) ρ = 1.0, S is not required

83. A signal is sampled at 8 kHz and is quantized using 8-bit uniform quantizer.
Assuming SNRq for a sinusoidal signal, the correct statement for PCM signal with
a bit rate of R is
(a) R = 32 kbps, SNRq = 25.8 dB (b) R = 64 kbps, SNRq = 49.8 dB
(c) R = 64 kbps, SNRq = 55.8 dB (d) R = 32 kbps, SNRq = 49.8 dB

89. A rectangular metal wave-guide filled with a dielectric material of relative
permitivity εr = 4 has the inside dimensions 3.0cm×1.2cm. The cut-off frequency
for the dominant mode is
(a) 2.5 GHz (b) 5.0 GHz (c) 10.0 GHz (d) 12.5 GHz

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