Page 1
GATE EC  2001
SECTION  A
1. This question consists of TWENTYFIVE subquestions (1.1 – 1.25) of ONE mark
each. For each of these subquestions, four possible alternatives (A,B, C and D)
are given, out of which ONLY ONE is correct. Indicate the correct answer by
darkening the appropriate bubble against the question number on the left hand
side of the Objective Response Sheet (ORS). You may use the answer book
provided for any rough work, if needed.
1.1 The voltage e
0
in figure 1.1 is
(a) 2V
(b)
4
3
V
(c) 4V
(d) 8V
1.2. If each branch of a Delta circuit has impedance 3 , Z then each branch of the
equivalent Wye circuit has impedance.
(a)
3
Z
(b) 3Z (c) 3 3Z (d)
3
Z
1.3. The transfer function of a system is given by ( )
( )
2
1
.
2
H s
s s
=

The impulse
response of the system is: (* denotes convolution, and U(t) is unit step function)
(a) (t
2
* e
2t
)U(t) (b) (t * e
2t
)U(t) (c) (te
2
t)U(t) (d) (te
2t
)U(t)
1.4. The admittance parameter Y
12
in the 2port network in Figure 1.4 is
(a) 0.2 mho
(b) 0.1 mho
(c) 0.05 mho
(d) 0.05 mho
1.5. The region of convergence of the ztransform of a unit step function is
(a) 1 z > (b) 1 z <
(c) (Real part of z) > 0 (d) (Real part of z) < 0
4O
2O
4O
12V
2O e O
+

20O
10O 5O E 1
I 1

E 2
I 2
Page 2
GATE EC  2001
SECTION  A
1. This question consists of TWENTYFIVE subquestions (1.1 – 1.25) of ONE mark
each. For each of these subquestions, four possible alternatives (A,B, C and D)
are given, out of which ONLY ONE is correct. Indicate the correct answer by
darkening the appropriate bubble against the question number on the left hand
side of the Objective Response Sheet (ORS). You may use the answer book
provided for any rough work, if needed.
1.1 The voltage e
0
in figure 1.1 is
(a) 2V
(b)
4
3
V
(c) 4V
(d) 8V
1.2. If each branch of a Delta circuit has impedance 3 , Z then each branch of the
equivalent Wye circuit has impedance.
(a)
3
Z
(b) 3Z (c) 3 3Z (d)
3
Z
1.3. The transfer function of a system is given by ( )
( )
2
1
.
2
H s
s s
=

The impulse
response of the system is: (* denotes convolution, and U(t) is unit step function)
(a) (t
2
* e
2t
)U(t) (b) (t * e
2t
)U(t) (c) (te
2
t)U(t) (d) (te
2t
)U(t)
1.4. The admittance parameter Y
12
in the 2port network in Figure 1.4 is
(a) 0.2 mho
(b) 0.1 mho
(c) 0.05 mho
(d) 0.05 mho
1.5. The region of convergence of the ztransform of a unit step function is
(a) 1 z > (b) 1 z <
(c) (Real part of z) > 0 (d) (Real part of z) < 0
4O
2O
4O
12V
2O e O
+

20O
10O 5O E 1
I 1

E 2
I 2
GATE EC  2001
1.6. The current gain of a BJT is
(a) g
m
r
0
(b)
m
o
g
r
(c) g
m
r
p
(d)
m
g
r
p
1.7. MOSFET can be used as a
(a) current controlled capacitor (b) voltage controlled capacitor
(c) current controlled inductor (d) voltage controlled inductor
1.8. The effective channel length of a MOSFET in saturation decreases with increase in
(a) gate voltage (b) drain voltage
(c) source voltage (d) body voltage
1.9. The ideal OPAMP has the following characteristics.
(a)
0
, , 0
i
R A R = 8 = 8 = (b)
0
0, , 0
i
R A R = = 8 =
(c)
0
, ,
i
R A R = 8 = 8 = 8 (d)
0
0, ,
i
R A R = = 8 = 8
1.10. The 2’s complement representation of –17 is
(a) 01110 (b) 01111 (c) 11110 (d) 10001
1.11. Consider the following two statements:
Statement 1: A stable multivibrator can be used for generating square wave.
Statement 2: B stable multivibrator can be used for storing binary information.
(a) Only statement 1 is correct
(b) Only statement 2 is correct
(c) Both the statements 1 and 2 are correct
(d) Both the statements 1 and 2 are incorrect
1.12. For the ring oscillator shown in Figure 1.12, the propagation delay of each
inverter is 100 pico second. What is the fundamental frequency of the oscillator
output?
(a) 10 MHz
(b) 100 MHz
(c) 1 GHz
(d) 2 GHz
1.13. An 8085 microprocessor based system uses a 4K × 8bit RAM whose starting
address is AA00. The address of the last byte in this RAM is
(a) 0FFFH (b) 1000 H (c) B9FF H (d) BA00 H
V 0
Page 3
GATE EC  2001
SECTION  A
1. This question consists of TWENTYFIVE subquestions (1.1 – 1.25) of ONE mark
each. For each of these subquestions, four possible alternatives (A,B, C and D)
are given, out of which ONLY ONE is correct. Indicate the correct answer by
darkening the appropriate bubble against the question number on the left hand
side of the Objective Response Sheet (ORS). You may use the answer book
provided for any rough work, if needed.
1.1 The voltage e
0
in figure 1.1 is
(a) 2V
(b)
4
3
V
(c) 4V
(d) 8V
1.2. If each branch of a Delta circuit has impedance 3 , Z then each branch of the
equivalent Wye circuit has impedance.
(a)
3
Z
(b) 3Z (c) 3 3Z (d)
3
Z
1.3. The transfer function of a system is given by ( )
( )
2
1
.
2
H s
s s
=

The impulse
response of the system is: (* denotes convolution, and U(t) is unit step function)
(a) (t
2
* e
2t
)U(t) (b) (t * e
2t
)U(t) (c) (te
2
t)U(t) (d) (te
2t
)U(t)
1.4. The admittance parameter Y
12
in the 2port network in Figure 1.4 is
(a) 0.2 mho
(b) 0.1 mho
(c) 0.05 mho
(d) 0.05 mho
1.5. The region of convergence of the ztransform of a unit step function is
(a) 1 z > (b) 1 z <
(c) (Real part of z) > 0 (d) (Real part of z) < 0
4O
2O
4O
12V
2O e O
+

20O
10O 5O E 1
I 1

E 2
I 2
GATE EC  2001
1.6. The current gain of a BJT is
(a) g
m
r
0
(b)
m
o
g
r
(c) g
m
r
p
(d)
m
g
r
p
1.7. MOSFET can be used as a
(a) current controlled capacitor (b) voltage controlled capacitor
(c) current controlled inductor (d) voltage controlled inductor
1.8. The effective channel length of a MOSFET in saturation decreases with increase in
(a) gate voltage (b) drain voltage
(c) source voltage (d) body voltage
1.9. The ideal OPAMP has the following characteristics.
(a)
0
, , 0
i
R A R = 8 = 8 = (b)
0
0, , 0
i
R A R = = 8 =
(c)
0
, ,
i
R A R = 8 = 8 = 8 (d)
0
0, ,
i
R A R = = 8 = 8
1.10. The 2’s complement representation of –17 is
(a) 01110 (b) 01111 (c) 11110 (d) 10001
1.11. Consider the following two statements:
Statement 1: A stable multivibrator can be used for generating square wave.
Statement 2: B stable multivibrator can be used for storing binary information.
(a) Only statement 1 is correct
(b) Only statement 2 is correct
(c) Both the statements 1 and 2 are correct
(d) Both the statements 1 and 2 are incorrect
1.12. For the ring oscillator shown in Figure 1.12, the propagation delay of each
inverter is 100 pico second. What is the fundamental frequency of the oscillator
output?
(a) 10 MHz
(b) 100 MHz
(c) 1 GHz
(d) 2 GHz
1.13. An 8085 microprocessor based system uses a 4K × 8bit RAM whose starting
address is AA00. The address of the last byte in this RAM is
(a) 0FFFH (b) 1000 H (c) B9FF H (d) BA00 H
V 0
GATE EC  2001
s x x
j?
K=0 K=0
K=5
8 K
K=1
3 2
K=8
1
1.14. The equivalent of the block diagram in Figure
1.14 is given in
(a) (b)
(c) (d)
15. If the characteristic equation of a closedloop system is
2
2 2 0 s s + + = , then the
system is
(a) over damped (b) critically damped
(c) underdamped (d) undamped
1.16. The rootlocus diagram for a closed loop feedback system is shown in Figure
1.16. The system is overdamped.
(a) only if 0 =K = 1
(b) only if 1 < K < 5
(c) only if K > 5
(d) if 0 =K < 1 or K > 5
E
F
G 1 G 2
H
C
E
F
G 1
H/G 2
C
E
F
G 1G 2
HG 2
C
E
F
G 1
HG 2
C
E
F
G 1G 2
H/G 2
C
Page 4
GATE EC  2001
SECTION  A
1. This question consists of TWENTYFIVE subquestions (1.1 – 1.25) of ONE mark
each. For each of these subquestions, four possible alternatives (A,B, C and D)
are given, out of which ONLY ONE is correct. Indicate the correct answer by
darkening the appropriate bubble against the question number on the left hand
side of the Objective Response Sheet (ORS). You may use the answer book
provided for any rough work, if needed.
1.1 The voltage e
0
in figure 1.1 is
(a) 2V
(b)
4
3
V
(c) 4V
(d) 8V
1.2. If each branch of a Delta circuit has impedance 3 , Z then each branch of the
equivalent Wye circuit has impedance.
(a)
3
Z
(b) 3Z (c) 3 3Z (d)
3
Z
1.3. The transfer function of a system is given by ( )
( )
2
1
.
2
H s
s s
=

The impulse
response of the system is: (* denotes convolution, and U(t) is unit step function)
(a) (t
2
* e
2t
)U(t) (b) (t * e
2t
)U(t) (c) (te
2
t)U(t) (d) (te
2t
)U(t)
1.4. The admittance parameter Y
12
in the 2port network in Figure 1.4 is
(a) 0.2 mho
(b) 0.1 mho
(c) 0.05 mho
(d) 0.05 mho
1.5. The region of convergence of the ztransform of a unit step function is
(a) 1 z > (b) 1 z <
(c) (Real part of z) > 0 (d) (Real part of z) < 0
4O
2O
4O
12V
2O e O
+

20O
10O 5O E 1
I 1

E 2
I 2
GATE EC  2001
1.6. The current gain of a BJT is
(a) g
m
r
0
(b)
m
o
g
r
(c) g
m
r
p
(d)
m
g
r
p
1.7. MOSFET can be used as a
(a) current controlled capacitor (b) voltage controlled capacitor
(c) current controlled inductor (d) voltage controlled inductor
1.8. The effective channel length of a MOSFET in saturation decreases with increase in
(a) gate voltage (b) drain voltage
(c) source voltage (d) body voltage
1.9. The ideal OPAMP has the following characteristics.
(a)
0
, , 0
i
R A R = 8 = 8 = (b)
0
0, , 0
i
R A R = = 8 =
(c)
0
, ,
i
R A R = 8 = 8 = 8 (d)
0
0, ,
i
R A R = = 8 = 8
1.10. The 2’s complement representation of –17 is
(a) 01110 (b) 01111 (c) 11110 (d) 10001
1.11. Consider the following two statements:
Statement 1: A stable multivibrator can be used for generating square wave.
Statement 2: B stable multivibrator can be used for storing binary information.
(a) Only statement 1 is correct
(b) Only statement 2 is correct
(c) Both the statements 1 and 2 are correct
(d) Both the statements 1 and 2 are incorrect
1.12. For the ring oscillator shown in Figure 1.12, the propagation delay of each
inverter is 100 pico second. What is the fundamental frequency of the oscillator
output?
(a) 10 MHz
(b) 100 MHz
(c) 1 GHz
(d) 2 GHz
1.13. An 8085 microprocessor based system uses a 4K × 8bit RAM whose starting
address is AA00. The address of the last byte in this RAM is
(a) 0FFFH (b) 1000 H (c) B9FF H (d) BA00 H
V 0
GATE EC  2001
s x x
j?
K=0 K=0
K=5
8 K
K=1
3 2
K=8
1
1.14. The equivalent of the block diagram in Figure
1.14 is given in
(a) (b)
(c) (d)
15. If the characteristic equation of a closedloop system is
2
2 2 0 s s + + = , then the
system is
(a) over damped (b) critically damped
(c) underdamped (d) undamped
1.16. The rootlocus diagram for a closed loop feedback system is shown in Figure
1.16. The system is overdamped.
(a) only if 0 =K = 1
(b) only if 1 < K < 5
(c) only if K > 5
(d) if 0 =K < 1 or K > 5
E
F
G 1 G 2
H
C
E
F
G 1
H/G 2
C
E
F
G 1G 2
HG 2
C
E
F
G 1
HG 2
C
E
F
G 1G 2
H/G 2
C
GATE EC  2001
1.17. The Nyquist plot for the openloop transfer function G(s) of a unity negative
feedback system is shown in figure 1.17 if G(s) has no pole in the right half of s
plane, the number of roots of the system characteristic equation in the right half
of splane is
(a) 0
(b) 1
(c) 2
(d) 3
1.18. Let d(t) denote the delta function. The value of the integral ( )
3
cos
2
t
t dt d
8
8
? ?
? ?
? ?
?
is
(a) 1 (b) 1 (c) 0 (d)
2
p
1.19. A band limited signal is sampled at the Nyquist rate. The signal can be recovered
by passing the samples through
(a) an RC filter (b) an envelope detector
(c) a PLL
(d) an ideal lowpass filter with appropriate bandwidth
1.20. The PDF of a Gaussian random variable X is given by ( )
( )
2
4
18
1
3 2
x
x
P x e
p
 
= . The
probability of the event {X = 4} is
(a)
1
2
(b)
1
3 2p
(c) 0 (d)
1
4
1.21. If a signal f(t) has energy E, the energy of the signal f(2t) is equal to
(a) E (b)
2
E
(c) 2E (d) 4E
1.22. A transmission line is distortionless if
(a)
1
RL
GC
= (b) RL = GC (c) LG = RC (d) RG = LC
1
I m(s)
G(s)Plane
R e(s)
Page 5
GATE EC  2001
SECTION  A
1. This question consists of TWENTYFIVE subquestions (1.1 – 1.25) of ONE mark
each. For each of these subquestions, four possible alternatives (A,B, C and D)
are given, out of which ONLY ONE is correct. Indicate the correct answer by
darkening the appropriate bubble against the question number on the left hand
side of the Objective Response Sheet (ORS). You may use the answer book
provided for any rough work, if needed.
1.1 The voltage e
0
in figure 1.1 is
(a) 2V
(b)
4
3
V
(c) 4V
(d) 8V
1.2. If each branch of a Delta circuit has impedance 3 , Z then each branch of the
equivalent Wye circuit has impedance.
(a)
3
Z
(b) 3Z (c) 3 3Z (d)
3
Z
1.3. The transfer function of a system is given by ( )
( )
2
1
.
2
H s
s s
=

The impulse
response of the system is: (* denotes convolution, and U(t) is unit step function)
(a) (t
2
* e
2t
)U(t) (b) (t * e
2t
)U(t) (c) (te
2
t)U(t) (d) (te
2t
)U(t)
1.4. The admittance parameter Y
12
in the 2port network in Figure 1.4 is
(a) 0.2 mho
(b) 0.1 mho
(c) 0.05 mho
(d) 0.05 mho
1.5. The region of convergence of the ztransform of a unit step function is
(a) 1 z > (b) 1 z <
(c) (Real part of z) > 0 (d) (Real part of z) < 0
4O
2O
4O
12V
2O e O
+

20O
10O 5O E 1
I 1

E 2
I 2
GATE EC  2001
1.6. The current gain of a BJT is
(a) g
m
r
0
(b)
m
o
g
r
(c) g
m
r
p
(d)
m
g
r
p
1.7. MOSFET can be used as a
(a) current controlled capacitor (b) voltage controlled capacitor
(c) current controlled inductor (d) voltage controlled inductor
1.8. The effective channel length of a MOSFET in saturation decreases with increase in
(a) gate voltage (b) drain voltage
(c) source voltage (d) body voltage
1.9. The ideal OPAMP has the following characteristics.
(a)
0
, , 0
i
R A R = 8 = 8 = (b)
0
0, , 0
i
R A R = = 8 =
(c)
0
, ,
i
R A R = 8 = 8 = 8 (d)
0
0, ,
i
R A R = = 8 = 8
1.10. The 2’s complement representation of –17 is
(a) 01110 (b) 01111 (c) 11110 (d) 10001
1.11. Consider the following two statements:
Statement 1: A stable multivibrator can be used for generating square wave.
Statement 2: B stable multivibrator can be used for storing binary information.
(a) Only statement 1 is correct
(b) Only statement 2 is correct
(c) Both the statements 1 and 2 are correct
(d) Both the statements 1 and 2 are incorrect
1.12. For the ring oscillator shown in Figure 1.12, the propagation delay of each
inverter is 100 pico second. What is the fundamental frequency of the oscillator
output?
(a) 10 MHz
(b) 100 MHz
(c) 1 GHz
(d) 2 GHz
1.13. An 8085 microprocessor based system uses a 4K × 8bit RAM whose starting
address is AA00. The address of the last byte in this RAM is
(a) 0FFFH (b) 1000 H (c) B9FF H (d) BA00 H
V 0
GATE EC  2001
s x x
j?
K=0 K=0
K=5
8 K
K=1
3 2
K=8
1
1.14. The equivalent of the block diagram in Figure
1.14 is given in
(a) (b)
(c) (d)
15. If the characteristic equation of a closedloop system is
2
2 2 0 s s + + = , then the
system is
(a) over damped (b) critically damped
(c) underdamped (d) undamped
1.16. The rootlocus diagram for a closed loop feedback system is shown in Figure
1.16. The system is overdamped.
(a) only if 0 =K = 1
(b) only if 1 < K < 5
(c) only if K > 5
(d) if 0 =K < 1 or K > 5
E
F
G 1 G 2
H
C
E
F
G 1
H/G 2
C
E
F
G 1G 2
HG 2
C
E
F
G 1
HG 2
C
E
F
G 1G 2
H/G 2
C
GATE EC  2001
1.17. The Nyquist plot for the openloop transfer function G(s) of a unity negative
feedback system is shown in figure 1.17 if G(s) has no pole in the right half of s
plane, the number of roots of the system characteristic equation in the right half
of splane is
(a) 0
(b) 1
(c) 2
(d) 3
1.18. Let d(t) denote the delta function. The value of the integral ( )
3
cos
2
t
t dt d
8
8
? ?
? ?
? ?
?
is
(a) 1 (b) 1 (c) 0 (d)
2
p
1.19. A band limited signal is sampled at the Nyquist rate. The signal can be recovered
by passing the samples through
(a) an RC filter (b) an envelope detector
(c) a PLL
(d) an ideal lowpass filter with appropriate bandwidth
1.20. The PDF of a Gaussian random variable X is given by ( )
( )
2
4
18
1
3 2
x
x
P x e
p
 
= . The
probability of the event {X = 4} is
(a)
1
2
(b)
1
3 2p
(c) 0 (d)
1
4
1.21. If a signal f(t) has energy E, the energy of the signal f(2t) is equal to
(a) E (b)
2
E
(c) 2E (d) 4E
1.22. A transmission line is distortionless if
(a)
1
RL
GC
= (b) RL = GC (c) LG = RC (d) RG = LC
1
I m(s)
G(s)Plane
R e(s)
GATE EC  2001
1.23. If a plane electromagnetic wave satisfies the equation
2 2
2
2 2
,
x x
E E
c
x t
? ?
=
? ?
the wave
propagates in the
(a) xdirection (b) zdirection
(c) ydirection
(d) xy plane at an angle of 45° between the x and z directions
1.24. The phase velocity of waves propagating in a hollow metal waveguide is
(a) greater than the velocity of light in free space.
(b) less than the velocity of light in free space.
(c) equal to the velocity of light in free space.
(d) equal to the group velocity.
1.25. The dominant mode in a rectangular waveguide is TE
10
, because this mode has
(a) no attenuation (b) no cutoff
(c) no magnetic field component (d) the highest cutoff wavelength
2. This question consists of TWENTYFIVE subquestions (2.1 – 2.25) of TWO marks
each. For each of these subquestions, four possible alternatives (A, B, C and D)
are given, out of which ONLY ONE is correct. Indicate the correct answer by
darkening the appropriate bubble against the question number on the left hand
side of the Objective Response Sheet (ORS). You may use the answer book
provided for any rough work, if needed.
2.1 The voltage e
0
in figure 2.1 is
(a) 48 V (b) 24 V
(c) 36 V (d) 28 V
2.2. In figure 2.2, the value of the load resistor R which maximizes the power
delivered to it is
(a) 14.14O
(b) 10O
(c) 200O
(d) 28.28O
10O 8A
2O
e 0
16V
6O
12O
+

R
1H
10O
~ E mcos10t
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