Electronics and Communication Engineering (EC) 1992 GATE Paper without solution

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``` Page 1

GATE EC - 1992

Time: 3 hours   Maximum Marks: 200 Part A: 80 Marks Part B: 120 Marks
1. This paper consists of two parts: “Part A” and “Part B”.
2. Part A contains 40 questions, each carrying 2 marks.
3. Part B contains 15 questions, each carrying 8 marks.
4. Read the instructions given at the beginning of each part carefully.
5. Attempt ALL questions.
6. There is no negative marking.
PART – A
1.1 Relative to a given fixed tree of a network,
(a) Link currents form an independent set
(b) Branch voltage from an independent set
(c) Link currents from an independent set
(d) Branch voltage from an independent set
1.2 For a 2-port network to be reciprocal
(a)
11 22
z z = (b)
21 12
y y = (c)
21 12
h h = - (d) 0 AD BC - =
1.3 For the series R-L circuit of figure(a), the partial fissure diagram at a certain
frequency is shown in figure (b).The operating frequency of the circuit is:
(a) equal to the resonance frequency
(b) less than the resonance frequency
(c) greater than resonance frequency (d) not zero
1.4 For the compensated attenuator of figure, the impulse response under the
condition
1 1 2 2
R C R C = is:
(a) ( )
1 1
1
2
1 2
1
R C
R
e u t
R R
? ?
- ? ?
+
? ?
? ?

(b) ( )
2
1 2
R
t
R R
d
+
(c) ( )
2
1 2
R
u t
R R +
(d) ( )
1 1
1
2
1 2
1 .
R C
R
e u t
R R
-
+
+
-
V
+
- +
-
R V L V
C V
+
-
(a)
R V
V
C V
(b)
+
-
+
-
C 2
C 1
V 1(t)
V 2(t)
R 1
R 2(t)
C
Page 2

GATE EC - 1992

Time: 3 hours   Maximum Marks: 200 Part A: 80 Marks Part B: 120 Marks
1. This paper consists of two parts: “Part A” and “Part B”.
2. Part A contains 40 questions, each carrying 2 marks.
3. Part B contains 15 questions, each carrying 8 marks.
4. Read the instructions given at the beginning of each part carefully.
5. Attempt ALL questions.
6. There is no negative marking.
PART – A
1.1 Relative to a given fixed tree of a network,
(a) Link currents form an independent set
(b) Branch voltage from an independent set
(c) Link currents from an independent set
(d) Branch voltage from an independent set
1.2 For a 2-port network to be reciprocal
(a)
11 22
z z = (b)
21 12
y y = (c)
21 12
h h = - (d) 0 AD BC - =
1.3 For the series R-L circuit of figure(a), the partial fissure diagram at a certain
frequency is shown in figure (b).The operating frequency of the circuit is:
(a) equal to the resonance frequency
(b) less than the resonance frequency
(c) greater than resonance frequency (d) not zero
1.4 For the compensated attenuator of figure, the impulse response under the
condition
1 1 2 2
R C R C = is:
(a) ( )
1 1
1
2
1 2
1
R C
R
e u t
R R
? ?
- ? ?
+
? ?
? ?

(b) ( )
2
1 2
R
t
R R
d
+
(c) ( )
2
1 2
R
u t
R R +
(d) ( )
1 1
1
2
1 2
1 .
R C
R
e u t
R R
-
+
+
-
V
+
- +
-
R V L V
C V
+
-
(a)
R V
V
C V
(b)
+
-
+
-
C 2
C 1
V 1(t)
V 2(t)
R 1
R 2(t)
C
GATE EC - 1992

1.5 Of the four networks,
1 2 3 4
, , and N N N N of figure, the networks having identical
driving point functions are
(a)
1 1
and N N (b)
2 4
and N N (c)
1 3
and N N (d)
1 4
and N N
1.6 A linear time invariant system is described by the state variable model
1 1 1
2 2 2
1 0 0
1 2
0 2 1
x x x
u
x x x
- ? ? ? ? ? ? ? ? ? ?
= + = ? ?
? ? ? ? ? ? ? ? ? ? ? ?
-
? ? ? ? ? ? ? ? ? ?
(a) The system is completely controllable
(b) The system is not completely controllable
(c) The system is completely observable
(d) The system is not completely observable
1.7 A process with open-loop model ( )
4
1
sT
ke
G s
s t
-
=
+
is controlled by a PID controller.
For this process
(a) the integral mode improves transient performance
(b) the integral mode improves steady state performance
(c) the derivative mode improves transient performance
(d) the derivative mode improves steady state performance
1.8 A linear discrete time system has the characteristic equation,
3
0.81 0. z z - = The
system
(a) is stable (b) is marginally stable
(c) in unstable
(d) stability cannot be assessed from the given information
2
1
2
1
1
N 1
2
1
1
N 2
2
2
1
1
N 3
1
1
1
1
N 4
2
Page 3

GATE EC - 1992

Time: 3 hours   Maximum Marks: 200 Part A: 80 Marks Part B: 120 Marks
1. This paper consists of two parts: “Part A” and “Part B”.
2. Part A contains 40 questions, each carrying 2 marks.
3. Part B contains 15 questions, each carrying 8 marks.
4. Read the instructions given at the beginning of each part carefully.
5. Attempt ALL questions.
6. There is no negative marking.
PART – A
1.1 Relative to a given fixed tree of a network,
(a) Link currents form an independent set
(b) Branch voltage from an independent set
(c) Link currents from an independent set
(d) Branch voltage from an independent set
1.2 For a 2-port network to be reciprocal
(a)
11 22
z z = (b)
21 12
y y = (c)
21 12
h h = - (d) 0 AD BC - =
1.3 For the series R-L circuit of figure(a), the partial fissure diagram at a certain
frequency is shown in figure (b).The operating frequency of the circuit is:
(a) equal to the resonance frequency
(b) less than the resonance frequency
(c) greater than resonance frequency (d) not zero
1.4 For the compensated attenuator of figure, the impulse response under the
condition
1 1 2 2
R C R C = is:
(a) ( )
1 1
1
2
1 2
1
R C
R
e u t
R R
? ?
- ? ?
+
? ?
? ?

(b) ( )
2
1 2
R
t
R R
d
+
(c) ( )
2
1 2
R
u t
R R +
(d) ( )
1 1
1
2
1 2
1 .
R C
R
e u t
R R
-
+
+
-
V
+
- +
-
R V L V
C V
+
-
(a)
R V
V
C V
(b)
+
-
+
-
C 2
C 1
V 1(t)
V 2(t)
R 1
R 2(t)
C
GATE EC - 1992

1.5 Of the four networks,
1 2 3 4
, , and N N N N of figure, the networks having identical
driving point functions are
(a)
1 1
and N N (b)
2 4
and N N (c)
1 3
and N N (d)
1 4
and N N
1.6 A linear time invariant system is described by the state variable model
1 1 1
2 2 2
1 0 0
1 2
0 2 1
x x x
u
x x x
- ? ? ? ? ? ? ? ? ? ?
= + = ? ?
? ? ? ? ? ? ? ? ? ? ? ?
-
? ? ? ? ? ? ? ? ? ?
(a) The system is completely controllable
(b) The system is not completely controllable
(c) The system is completely observable
(d) The system is not completely observable
1.7 A process with open-loop model ( )
4
1
sT
ke
G s
s t
-
=
+
is controlled by a PID controller.
For this process
(a) the integral mode improves transient performance
(b) the integral mode improves steady state performance
(c) the derivative mode improves transient performance
(d) the derivative mode improves steady state performance
1.8 A linear discrete time system has the characteristic equation,
3
0.81 0. z z - = The
system
(a) is stable (b) is marginally stable
(c) in unstable
(d) stability cannot be assessed from the given information
2
1
2
1
1
N 1
2
1
1
N 2
2
2
1
1
N 3
1
1
1
1
N 4
2
GATE EC - 1992

1.9 Bode plot of a stable system is shown in figure. The transfer function of the
system is _______.
1.10 Given a unity feedback system with open loop transfer function,
( )
( )( )
.
1 2
K
G s
s s s
=
+ +
The root locus plot of the system is of the form.
1.11 A semiconductor is irradiated with light such that carriers are uniformly
generated throughout its volume. The semiconductor is n-type with
19
10
D
N = per
3
. cm If the excess electron concentration in the steady state id
15
10 n ? = per
3
cm and if 10 sec
p
t µ = [minority carrier life time] the generation rate due to
(a) is
20 3
10 pair/cm / e h s - (b) is
24 3
10 pair/cm / e h s -
(c) is
10 3
10 pair/cm / e h s -
(d) cannot be determined as the given data is insufficient
1.12  A P – N junction in series with a 100 ohms resistor, is forward biased so that a
current of 100 mA flows. If the 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 given by
(a) 0 mA (b) 100 mA (c) 200 mA (d) 50 mA
dB
20
log ?
× × ×
s
j?
× × ×
s
j?
× × ×
s
j?
× × ×
j?
s
Page 4

GATE EC - 1992

Time: 3 hours   Maximum Marks: 200 Part A: 80 Marks Part B: 120 Marks
1. This paper consists of two parts: “Part A” and “Part B”.
2. Part A contains 40 questions, each carrying 2 marks.
3. Part B contains 15 questions, each carrying 8 marks.
4. Read the instructions given at the beginning of each part carefully.
5. Attempt ALL questions.
6. There is no negative marking.
PART – A
1.1 Relative to a given fixed tree of a network,
(a) Link currents form an independent set
(b) Branch voltage from an independent set
(c) Link currents from an independent set
(d) Branch voltage from an independent set
1.2 For a 2-port network to be reciprocal
(a)
11 22
z z = (b)
21 12
y y = (c)
21 12
h h = - (d) 0 AD BC - =
1.3 For the series R-L circuit of figure(a), the partial fissure diagram at a certain
frequency is shown in figure (b).The operating frequency of the circuit is:
(a) equal to the resonance frequency
(b) less than the resonance frequency
(c) greater than resonance frequency (d) not zero
1.4 For the compensated attenuator of figure, the impulse response under the
condition
1 1 2 2
R C R C = is:
(a) ( )
1 1
1
2
1 2
1
R C
R
e u t
R R
? ?
- ? ?
+
? ?
? ?

(b) ( )
2
1 2
R
t
R R
d
+
(c) ( )
2
1 2
R
u t
R R +
(d) ( )
1 1
1
2
1 2
1 .
R C
R
e u t
R R
-
+
+
-
V
+
- +
-
R V L V
C V
+
-
(a)
R V
V
C V
(b)
+
-
+
-
C 2
C 1
V 1(t)
V 2(t)
R 1
R 2(t)
C
GATE EC - 1992

1.5 Of the four networks,
1 2 3 4
, , and N N N N of figure, the networks having identical
driving point functions are
(a)
1 1
and N N (b)
2 4
and N N (c)
1 3
and N N (d)
1 4
and N N
1.6 A linear time invariant system is described by the state variable model
1 1 1
2 2 2
1 0 0
1 2
0 2 1
x x x
u
x x x
- ? ? ? ? ? ? ? ? ? ?
= + = ? ?
? ? ? ? ? ? ? ? ? ? ? ?
-
? ? ? ? ? ? ? ? ? ?
(a) The system is completely controllable
(b) The system is not completely controllable
(c) The system is completely observable
(d) The system is not completely observable
1.7 A process with open-loop model ( )
4
1
sT
ke
G s
s t
-
=
+
is controlled by a PID controller.
For this process
(a) the integral mode improves transient performance
(b) the integral mode improves steady state performance
(c) the derivative mode improves transient performance
(d) the derivative mode improves steady state performance
1.8 A linear discrete time system has the characteristic equation,
3
0.81 0. z z - = The
system
(a) is stable (b) is marginally stable
(c) in unstable
(d) stability cannot be assessed from the given information
2
1
2
1
1
N 1
2
1
1
N 2
2
2
1
1
N 3
1
1
1
1
N 4
2
GATE EC - 1992

1.9 Bode plot of a stable system is shown in figure. The transfer function of the
system is _______.
1.10 Given a unity feedback system with open loop transfer function,
( )
( )( )
.
1 2
K
G s
s s s
=
+ +
The root locus plot of the system is of the form.
1.11 A semiconductor is irradiated with light such that carriers are uniformly
generated throughout its volume. The semiconductor is n-type with
19
10
D
N = per
3
. cm If the excess electron concentration in the steady state id
15
10 n ? = per
3
cm and if 10 sec
p
t µ = [minority carrier life time] the generation rate due to
(a) is
20 3
10 pair/cm / e h s - (b) is
24 3
10 pair/cm / e h s -
(c) is
10 3
10 pair/cm / e h s -
(d) cannot be determined as the given data is insufficient
1.12  A P – N junction in series with a 100 ohms resistor, is forward biased so that a
current of 100 mA flows. If the 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 given by
(a) 0 mA (b) 100 mA (c) 200 mA (d) 50 mA
dB
20
log ?
× × ×
s
j?
× × ×
s
j?
× × ×
s
j?
× × ×
j?
s
GATE EC - 1992

1.13 An infra red LED is usually fabricated from
(a) Ge (b) Si (c) Ga As (d) Ga As P
1.14 In a transistor having finite B, the forward bias across the base emitter junction
is kept constant and the reverse bias across the collector base junction is
increased. Neglecting the leakage across the collector base junction and the
depletion region generating current, the base current will ____.
(increase/decrease/remain constant).
1.15 An n-channel JFET has a pinch-off voltage of ( ) 5 , max 20 ,
p DS
V V V V = - = and
2 / .
m
mA V d = The minimum ‘ON’ resistance is achieved in the JEFT for
(a) 7 and 0
GS DS
V V V V = - = (b) 7 and 0
GS DS
V V V V = =
(c) 0 and 20
GS DS
V V V V = = (d) 7 and 20
GS DS
V V V V = - =
1.16 The JFET in the circuit shown in figure has an 10 and 5 .
DSS P
I mA V V = = The value
of the resistance
s
R for a drain current 6.4
DS
I mA = is (select the nearest value)
(a) 150 ohms (b) 470 ohms (c) 560 ohms (d) 1 kilo ohm
1.17 An op.amp has an offset voltage of 1 mV and is ideal in all other respects. If this
op.amp is used in the circuit shown in figure, the output voltage will be (select
the nearest value)
(a) 1 mV (b) 1 V (c) ± 1 V (d) 0 V
R S
I DS
10V
+
-
-
+
1KO
1MO
V O
Page 5

GATE EC - 1992

Time: 3 hours   Maximum Marks: 200 Part A: 80 Marks Part B: 120 Marks
1. This paper consists of two parts: “Part A” and “Part B”.
2. Part A contains 40 questions, each carrying 2 marks.
3. Part B contains 15 questions, each carrying 8 marks.
4. Read the instructions given at the beginning of each part carefully.
5. Attempt ALL questions.
6. There is no negative marking.
PART – A
1.1 Relative to a given fixed tree of a network,
(a) Link currents form an independent set
(b) Branch voltage from an independent set
(c) Link currents from an independent set
(d) Branch voltage from an independent set
1.2 For a 2-port network to be reciprocal
(a)
11 22
z z = (b)
21 12
y y = (c)
21 12
h h = - (d) 0 AD BC - =
1.3 For the series R-L circuit of figure(a), the partial fissure diagram at a certain
frequency is shown in figure (b).The operating frequency of the circuit is:
(a) equal to the resonance frequency
(b) less than the resonance frequency
(c) greater than resonance frequency (d) not zero
1.4 For the compensated attenuator of figure, the impulse response under the
condition
1 1 2 2
R C R C = is:
(a) ( )
1 1
1
2
1 2
1
R C
R
e u t
R R
? ?
- ? ?
+
? ?
? ?

(b) ( )
2
1 2
R
t
R R
d
+
(c) ( )
2
1 2
R
u t
R R +
(d) ( )
1 1
1
2
1 2
1 .
R C
R
e u t
R R
-
+
+
-
V
+
- +
-
R V L V
C V
+
-
(a)
R V
V
C V
(b)
+
-
+
-
C 2
C 1
V 1(t)
V 2(t)
R 1
R 2(t)
C
GATE EC - 1992

1.5 Of the four networks,
1 2 3 4
, , and N N N N of figure, the networks having identical
driving point functions are
(a)
1 1
and N N (b)
2 4
and N N (c)
1 3
and N N (d)
1 4
and N N
1.6 A linear time invariant system is described by the state variable model
1 1 1
2 2 2
1 0 0
1 2
0 2 1
x x x
u
x x x
- ? ? ? ? ? ? ? ? ? ?
= + = ? ?
? ? ? ? ? ? ? ? ? ? ? ?
-
? ? ? ? ? ? ? ? ? ?
(a) The system is completely controllable
(b) The system is not completely controllable
(c) The system is completely observable
(d) The system is not completely observable
1.7 A process with open-loop model ( )
4
1
sT
ke
G s
s t
-
=
+
is controlled by a PID controller.
For this process
(a) the integral mode improves transient performance
(b) the integral mode improves steady state performance
(c) the derivative mode improves transient performance
(d) the derivative mode improves steady state performance
1.8 A linear discrete time system has the characteristic equation,
3
0.81 0. z z - = The
system
(a) is stable (b) is marginally stable
(c) in unstable
(d) stability cannot be assessed from the given information
2
1
2
1
1
N 1
2
1
1
N 2
2
2
1
1
N 3
1
1
1
1
N 4
2
GATE EC - 1992

1.9 Bode plot of a stable system is shown in figure. The transfer function of the
system is _______.
1.10 Given a unity feedback system with open loop transfer function,
( )
( )( )
.
1 2
K
G s
s s s
=
+ +
The root locus plot of the system is of the form.
1.11 A semiconductor is irradiated with light such that carriers are uniformly
generated throughout its volume. The semiconductor is n-type with
19
10
D
N = per
3
. cm If the excess electron concentration in the steady state id
15
10 n ? = per
3
cm and if 10 sec
p
t µ = [minority carrier life time] the generation rate due to
(a) is
20 3
10 pair/cm / e h s - (b) is
24 3
10 pair/cm / e h s -
(c) is
10 3
10 pair/cm / e h s -
(d) cannot be determined as the given data is insufficient
1.12  A P – N junction in series with a 100 ohms resistor, is forward biased so that a
current of 100 mA flows. If the 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 given by
(a) 0 mA (b) 100 mA (c) 200 mA (d) 50 mA
dB
20
log ?
× × ×
s
j?
× × ×
s
j?
× × ×
s
j?
× × ×
j?
s
GATE EC - 1992

1.13 An infra red LED is usually fabricated from
(a) Ge (b) Si (c) Ga As (d) Ga As P
1.14 In a transistor having finite B, the forward bias across the base emitter junction
is kept constant and the reverse bias across the collector base junction is
increased. Neglecting the leakage across the collector base junction and the
depletion region generating current, the base current will ____.
(increase/decrease/remain constant).
1.15 An n-channel JFET has a pinch-off voltage of ( ) 5 , max 20 ,
p DS
V V V V = - = and
2 / .
m
mA V d = The minimum ‘ON’ resistance is achieved in the JEFT for
(a) 7 and 0
GS DS
V V V V = - = (b) 7 and 0
GS DS
V V V V = =
(c) 0 and 20
GS DS
V V V V = = (d) 7 and 20
GS DS
V V V V = - =
1.16 The JFET in the circuit shown in figure has an 10 and 5 .
DSS P
I mA V V = = The value
of the resistance
s
R for a drain current 6.4
DS
I mA = is (select the nearest value)
(a) 150 ohms (b) 470 ohms (c) 560 ohms (d) 1 kilo ohm
1.17 An op.amp has an offset voltage of 1 mV and is ideal in all other respects. If this
op.amp is used in the circuit shown in figure, the output voltage will be (select
the nearest value)
(a) 1 mV (b) 1 V (c) ± 1 V (d) 0 V
R S
I DS
10V
+
-
-
+
1KO
1MO
V O
GATE EC - 1992

1.18 If the transistors in figure, have high values of ß and a
BE
V of 0.65 volt, the
current I, flowing through the 2 kilo ohms resistance will be ______.
1.19. The circuit of figure uses an ideal op amp. For small positive values of ,
in
V the
circuit works as
(a) a halfwave rectifier
(b) a differentiator
(c) a logarithmic amplifier
(d) an exponential amplifier
1.20. Assume that the operational amplifier in figure is ideal. The current I, through the
1 K ohm resistor is ____.
1.21. The 6 V Zener diode shown in figure has zero zener resistance and a knee current
of 5 mA. The minimum value of R so that the voltage across it does not fall below
6 V is:
(a) 1.2 K ohms
(b) 80 ohms
(c) 50 ohms
(d) 0 ohms
-
+
I
2K
1kO
2kO
2mA
6.5kO
1.85kO
1.65kO
2kO
1kO
I

10V
-
+
V in
R

-
+
V out
10V
50O
V R
-
+
```

## FAQs on Electronics and Communication Engineering (EC) 1992 GATE Paper without solution

 1. What is Electronics and Communication Engineering (EC)?
Ans. Electronics and Communication Engineering (EC) is a field of engineering that deals with the design, development, and application of electronic devices, systems, and communication technologies. It involves the study of electronic circuits, digital systems, microprocessors, telecommunications, and signal processing.
 2. What is the significance of the 1992 GATE Paper in Electronics and Communication Engineering?
Ans. The 1992 GATE Paper in Electronics and Communication Engineering is significant as it is a past question paper for the Graduate Aptitude Test in Engineering (GATE) exam. GATE is a highly competitive exam conducted for admission to postgraduate programs in engineering and technology. Solving previous year question papers like the 1992 GATE Paper can help candidates understand the exam pattern, difficulty level, and identify important topics.
 3. What are some important topics that candidates should focus on for the Electronics and Communication Engineering GATE exam?
Ans. Some important topics for the Electronics and Communication Engineering GATE exam include analog and digital electronics, electromagnetic theory, control systems, communication systems, signals and systems, network theory, electronic devices and circuits, microprocessors and microcontrollers, and digital signal processing. Candidates should thoroughly study these topics to perform well in the exam.
 4. Are solutions available for the 1992 GATE Paper in Electronics and Communication Engineering?
Ans. Unfortunately, the given article does not provide solutions for the 1992 GATE Paper in Electronics and Communication Engineering. However, candidates can refer to various GATE preparation books, online resources, or coaching institutes that may provide solutions or explanations for the questions in the paper.
 5. How can solving previous year GATE papers benefit candidates preparing for the Electronics and Communication Engineering exam?
Ans. Solving previous year GATE papers can benefit candidates in multiple ways. It helps them understand the exam pattern, time management, and question difficulty level. It also helps in identifying important topics, improving problem-solving skills, and building confidence. Additionally, analyzing the solutions and mistakes made during practice can guide candidates in their preparation and help them perform better in the actual exam.
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