Electronics and Communication Engineering (EC) 2013 GATE Paper (Set C) without solution | GATE Past Year Papers for Practice (All Branches)

 Page 1


 
 
 
 
 
 
 
SESSION - 3 
 
 
 
 
 
 
 
 
Page 2


 
 
 
 
 
 
 
SESSION - 3 
 
 
 
 
 
 
 
 
2013                                                                                                                           Question Booklet Code                                                                           
 
EC-C 
 
1/24
EC : ELECTRONICS AND COMMUNICATION ENGINEERING 
 
Duration: Three Hours                       Maximum Marks: 100 
Read the following instructions carefully. 
 
1. Do not open the seal of the Question Booklet until you are asked to do so by the invigilator. 
2. Take out the Optical Response Sheet (ORS) from this Question Booklet without breaking the seal 
and read the instructions printed on the ORS carefully. If you find that either: 
a. The Question Booklet Code printed at the right hand top corner of this page does not match with 
the Question Booklet Code at the right hand top corner of the ORS or 
b. The Question Paper Code preceding the Registration number on the ORS is not EC,  
            then exchange the booklet immediately with a new sealed Question Booklet.  
3. On the right hand side of the ORS, using ONLY a black ink ballpoint pen, (i) darken the appropriate 
bubble under each digit of your registration number and (ii) write your registration number, your 
name and name of the examination centre and put your signature at the specified location.  
4. This Question Booklet contains 24 pages including blank pages for rough work. After you are 
permitted to open the seal, check all pages and report discrepancies, if any, to the invigilator. 
5. There are a total of 65 questions carrying 100 marks. All these questions are of objective type. Each 
question has only one correct answer. Questions must be answered on the left hand side of the ORS 
by darkening the appropriate bubble (marked A, B, C, D) using ONLY a black ink ballpoint pen 
against the question number. For each question darken the bubble of the correct answer. More 
than one answer bubbled against a question will be treated as an incorrect response. 
6. Since bubbles darkened by the black ink ballpoint pen cannot be erased, candidates should darken the 
bubbles in the ORS very carefully. 
7. Questions Q.1 – Q.25 carry 1 mark each. Questions Q.26 – Q.55 carry 2 marks each. The 2 marks 
questions include two pairs of common data questions and two pairs of linked answer questions. The 
answer to the second question of the linked answer questions depends on the answer to the first 
question of the pair. If the first question in the linked pair is wrongly answered or is not attempted, 
then the answer to the second question in the pair will not be evaluated. 
8. Questions Q.56 – Q.65 belong to General Aptitude (GA) section and carry a total of 15 marks. 
Questions Q.56 – Q.60 carry 1 mark each, and questions Q.61 – Q.65 carry 2 marks each. 
9. Questions not attempted will result in zero mark and wrong answers will result in NEGATIVE 
marks.  For all 1 mark questions, ? mark will be deducted for each wrong answer. For all 2 marks 
questions, ? mark will be deducted for each wrong answer.  However, in the case of the linked 
answer question pair, there will be negative marks only for wrong answer to the first question and no 
negative marks for wrong answer to the second question.  
10. Calculator is allowed whereas charts, graph sheets or tables are NOT allowed in the examination hall. 
11. Rough work can be done on the Question Booklet itself. Blank pages are provided at the end of the 
Question Booklet for rough work. 
12. Before the start of the examination, write your name and registration number in the space provided 
below using a black ink ballpoint pen. 
Name 
 
 
Registration Number 
EC 
       
 
 
C 
Page 3


 
 
 
 
 
 
 
SESSION - 3 
 
 
 
 
 
 
 
 
2013                                                                                                                           Question Booklet Code                                                                           
 
EC-C 
 
1/24
EC : ELECTRONICS AND COMMUNICATION ENGINEERING 
 
Duration: Three Hours                       Maximum Marks: 100 
Read the following instructions carefully. 
 
1. Do not open the seal of the Question Booklet until you are asked to do so by the invigilator. 
2. Take out the Optical Response Sheet (ORS) from this Question Booklet without breaking the seal 
and read the instructions printed on the ORS carefully. If you find that either: 
a. The Question Booklet Code printed at the right hand top corner of this page does not match with 
the Question Booklet Code at the right hand top corner of the ORS or 
b. The Question Paper Code preceding the Registration number on the ORS is not EC,  
            then exchange the booklet immediately with a new sealed Question Booklet.  
3. On the right hand side of the ORS, using ONLY a black ink ballpoint pen, (i) darken the appropriate 
bubble under each digit of your registration number and (ii) write your registration number, your 
name and name of the examination centre and put your signature at the specified location.  
4. This Question Booklet contains 24 pages including blank pages for rough work. After you are 
permitted to open the seal, check all pages and report discrepancies, if any, to the invigilator. 
5. There are a total of 65 questions carrying 100 marks. All these questions are of objective type. Each 
question has only one correct answer. Questions must be answered on the left hand side of the ORS 
by darkening the appropriate bubble (marked A, B, C, D) using ONLY a black ink ballpoint pen 
against the question number. For each question darken the bubble of the correct answer. More 
than one answer bubbled against a question will be treated as an incorrect response. 
6. Since bubbles darkened by the black ink ballpoint pen cannot be erased, candidates should darken the 
bubbles in the ORS very carefully. 
7. Questions Q.1 – Q.25 carry 1 mark each. Questions Q.26 – Q.55 carry 2 marks each. The 2 marks 
questions include two pairs of common data questions and two pairs of linked answer questions. The 
answer to the second question of the linked answer questions depends on the answer to the first 
question of the pair. If the first question in the linked pair is wrongly answered or is not attempted, 
then the answer to the second question in the pair will not be evaluated. 
8. Questions Q.56 – Q.65 belong to General Aptitude (GA) section and carry a total of 15 marks. 
Questions Q.56 – Q.60 carry 1 mark each, and questions Q.61 – Q.65 carry 2 marks each. 
9. Questions not attempted will result in zero mark and wrong answers will result in NEGATIVE 
marks.  For all 1 mark questions, ? mark will be deducted for each wrong answer. For all 2 marks 
questions, ? mark will be deducted for each wrong answer.  However, in the case of the linked 
answer question pair, there will be negative marks only for wrong answer to the first question and no 
negative marks for wrong answer to the second question.  
10. Calculator is allowed whereas charts, graph sheets or tables are NOT allowed in the examination hall. 
11. Rough work can be done on the Question Booklet itself. Blank pages are provided at the end of the 
Question Booklet for rough work. 
12. Before the start of the examination, write your name and registration number in the space provided 
below using a black ink ballpoint pen. 
Name 
 
 
Registration Number 
EC 
       
 
 
C 
2013                                                                                                                             ELECTRONICS & COMMN. ENGG.  -  EC                                                                                                                       
 
EC-C 2/24
Q.1 to Q.25 carry one mark each. 
 
Q.1 The bit rate of a digital communication system is R kbits/s. The modulation used is 32-QAM. The 
minimum bandwidth required for ISI free transmission is  
(A) R/10 Hz (B) R/10 kHz (C)  R/5 Hz (D)  R/5 kHz 
 
Q.2 For 8085 microprocessor, the following program is executed. 
 
          MVI A, 05H; 
          MVI B, 05H; 
PTR: ADD B; 
          DCR B; 
          JNZ PTR; 
          ADI 03H; 
          HLT; 
 
At the end of program, accumulator contains 
(A) 17H (B) 20H (C) 23H  (D)  05H 
 
Q.3 Consider a delta connection of resistors and its equivalent star connection as shown below. If all 
elements of the delta connection are scaled by a factor k, k> 0, the elements of the corresponding 
star equivalent will be scaled by a factor of 
R
B
R
C
R
b
R
a
R
c
R
A
 
(A) k
2
 (B) k (C)  1/k (D) k 
 
Q.4 In the circuit shown below what is the output voltage (V
out
) if a silicon transistor Q and an ideal  
op-amp are used? 
 
+15 V
– 15 V
5V
1 k? 
V
out
+
–
Q
 
 
(A) 15 V (B) 0.7 V   
(C)  0.7 V   (D)  15 V 
 
Page 4


 
 
 
 
 
 
 
SESSION - 3 
 
 
 
 
 
 
 
 
2013                                                                                                                           Question Booklet Code                                                                           
 
EC-C 
 
1/24
EC : ELECTRONICS AND COMMUNICATION ENGINEERING 
 
Duration: Three Hours                       Maximum Marks: 100 
Read the following instructions carefully. 
 
1. Do not open the seal of the Question Booklet until you are asked to do so by the invigilator. 
2. Take out the Optical Response Sheet (ORS) from this Question Booklet without breaking the seal 
and read the instructions printed on the ORS carefully. If you find that either: 
a. The Question Booklet Code printed at the right hand top corner of this page does not match with 
the Question Booklet Code at the right hand top corner of the ORS or 
b. The Question Paper Code preceding the Registration number on the ORS is not EC,  
            then exchange the booklet immediately with a new sealed Question Booklet.  
3. On the right hand side of the ORS, using ONLY a black ink ballpoint pen, (i) darken the appropriate 
bubble under each digit of your registration number and (ii) write your registration number, your 
name and name of the examination centre and put your signature at the specified location.  
4. This Question Booklet contains 24 pages including blank pages for rough work. After you are 
permitted to open the seal, check all pages and report discrepancies, if any, to the invigilator. 
5. There are a total of 65 questions carrying 100 marks. All these questions are of objective type. Each 
question has only one correct answer. Questions must be answered on the left hand side of the ORS 
by darkening the appropriate bubble (marked A, B, C, D) using ONLY a black ink ballpoint pen 
against the question number. For each question darken the bubble of the correct answer. More 
than one answer bubbled against a question will be treated as an incorrect response. 
6. Since bubbles darkened by the black ink ballpoint pen cannot be erased, candidates should darken the 
bubbles in the ORS very carefully. 
7. Questions Q.1 – Q.25 carry 1 mark each. Questions Q.26 – Q.55 carry 2 marks each. The 2 marks 
questions include two pairs of common data questions and two pairs of linked answer questions. The 
answer to the second question of the linked answer questions depends on the answer to the first 
question of the pair. If the first question in the linked pair is wrongly answered or is not attempted, 
then the answer to the second question in the pair will not be evaluated. 
8. Questions Q.56 – Q.65 belong to General Aptitude (GA) section and carry a total of 15 marks. 
Questions Q.56 – Q.60 carry 1 mark each, and questions Q.61 – Q.65 carry 2 marks each. 
9. Questions not attempted will result in zero mark and wrong answers will result in NEGATIVE 
marks.  For all 1 mark questions, ? mark will be deducted for each wrong answer. For all 2 marks 
questions, ? mark will be deducted for each wrong answer.  However, in the case of the linked 
answer question pair, there will be negative marks only for wrong answer to the first question and no 
negative marks for wrong answer to the second question.  
10. Calculator is allowed whereas charts, graph sheets or tables are NOT allowed in the examination hall. 
11. Rough work can be done on the Question Booklet itself. Blank pages are provided at the end of the 
Question Booklet for rough work. 
12. Before the start of the examination, write your name and registration number in the space provided 
below using a black ink ballpoint pen. 
Name 
 
 
Registration Number 
EC 
       
 
 
C 
2013                                                                                                                             ELECTRONICS & COMMN. ENGG.  -  EC                                                                                                                       
 
EC-C 2/24
Q.1 to Q.25 carry one mark each. 
 
Q.1 The bit rate of a digital communication system is R kbits/s. The modulation used is 32-QAM. The 
minimum bandwidth required for ISI free transmission is  
(A) R/10 Hz (B) R/10 kHz (C)  R/5 Hz (D)  R/5 kHz 
 
Q.2 For 8085 microprocessor, the following program is executed. 
 
          MVI A, 05H; 
          MVI B, 05H; 
PTR: ADD B; 
          DCR B; 
          JNZ PTR; 
          ADI 03H; 
          HLT; 
 
At the end of program, accumulator contains 
(A) 17H (B) 20H (C) 23H  (D)  05H 
 
Q.3 Consider a delta connection of resistors and its equivalent star connection as shown below. If all 
elements of the delta connection are scaled by a factor k, k> 0, the elements of the corresponding 
star equivalent will be scaled by a factor of 
R
B
R
C
R
b
R
a
R
c
R
A
 
(A) k
2
 (B) k (C)  1/k (D) k 
 
Q.4 In the circuit shown below what is the output voltage (V
out
) if a silicon transistor Q and an ideal  
op-amp are used? 
 
+15 V
– 15 V
5V
1 k? 
V
out
+
–
Q
 
 
(A) 15 V (B) 0.7 V   
(C)  0.7 V   (D)  15 V 
 
2013                                                                                                                             ELECTRONICS & COMMN. ENGG.  -  EC                                                                                                                       
 
EC-C 3/24
Q.5 
The Bode plot of a transfer function ) (s G is shown in the figure below.  
 
Gain (dB)
 
The gain ) ) ( log 20 ( s G is 32 dB and 8 - 
dB at 1 rad/s and 10 rad/s respectively. The phase is 
negative for all ?. Then ) (s G is  
(A) 
s
8 . 39
 (B) 
2
8 . 39
s
 (C)  
s
32
  (D)  
2
32
s
 
 
Q.6 The impulse response of a system is ) ( ) ( t u t t h = . For an input , ) 1 ( - t u the output is 
(A) ) (
2
2
t u
t
 
(B) ) 1 (
) 1 (
2
- - t u
t t
 
(C) ) 1 (
) 1 (
2
2
- - t u
t
 (D) ) 1 (
1
2
2
- - t u
t
 
 
Q.7 The divergence of the vector field ˆ ˆ ˆ
x y z
A xa ya za = + +
r
is 
(A) 0 (B) 1/3 (C) 1  (D) 3  
 
Q.8 The maximum value of ?
 
until which the approximation sin? ? ˜
 
holds to within 10% error is  
(A) 10° (B) 18° (C) 50° (D) 90° 
 
Q.9 In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or 
water vapor) produces 
(A)   superior quality oxide with a higher growth rate 
(B)   inferior quality oxide with a higher growth rate 
(C)   inferior quality oxide with a lower growth rate 
(D)   superior quality oxide with a lower growth rate 
 
Q.10 In a forward biased pn junction diode, the sequence of events that best describes the mechanism of 
current flow is 
(A)   injection, and subsequent diffusion and recombination of minority carriers 
(B)   injection, and subsequent drift and generation of minority carriers 
(C)   extraction, and subsequent diffusion and generation of minority carriers 
(D)   extraction, and subsequent drift and recombination of minority carriers 
Page 5


 
 
 
 
 
 
 
SESSION - 3 
 
 
 
 
 
 
 
 
2013                                                                                                                           Question Booklet Code                                                                           
 
EC-C 
 
1/24
EC : ELECTRONICS AND COMMUNICATION ENGINEERING 
 
Duration: Three Hours                       Maximum Marks: 100 
Read the following instructions carefully. 
 
1. Do not open the seal of the Question Booklet until you are asked to do so by the invigilator. 
2. Take out the Optical Response Sheet (ORS) from this Question Booklet without breaking the seal 
and read the instructions printed on the ORS carefully. If you find that either: 
a. The Question Booklet Code printed at the right hand top corner of this page does not match with 
the Question Booklet Code at the right hand top corner of the ORS or 
b. The Question Paper Code preceding the Registration number on the ORS is not EC,  
            then exchange the booklet immediately with a new sealed Question Booklet.  
3. On the right hand side of the ORS, using ONLY a black ink ballpoint pen, (i) darken the appropriate 
bubble under each digit of your registration number and (ii) write your registration number, your 
name and name of the examination centre and put your signature at the specified location.  
4. This Question Booklet contains 24 pages including blank pages for rough work. After you are 
permitted to open the seal, check all pages and report discrepancies, if any, to the invigilator. 
5. There are a total of 65 questions carrying 100 marks. All these questions are of objective type. Each 
question has only one correct answer. Questions must be answered on the left hand side of the ORS 
by darkening the appropriate bubble (marked A, B, C, D) using ONLY a black ink ballpoint pen 
against the question number. For each question darken the bubble of the correct answer. More 
than one answer bubbled against a question will be treated as an incorrect response. 
6. Since bubbles darkened by the black ink ballpoint pen cannot be erased, candidates should darken the 
bubbles in the ORS very carefully. 
7. Questions Q.1 – Q.25 carry 1 mark each. Questions Q.26 – Q.55 carry 2 marks each. The 2 marks 
questions include two pairs of common data questions and two pairs of linked answer questions. The 
answer to the second question of the linked answer questions depends on the answer to the first 
question of the pair. If the first question in the linked pair is wrongly answered or is not attempted, 
then the answer to the second question in the pair will not be evaluated. 
8. Questions Q.56 – Q.65 belong to General Aptitude (GA) section and carry a total of 15 marks. 
Questions Q.56 – Q.60 carry 1 mark each, and questions Q.61 – Q.65 carry 2 marks each. 
9. Questions not attempted will result in zero mark and wrong answers will result in NEGATIVE 
marks.  For all 1 mark questions, ? mark will be deducted for each wrong answer. For all 2 marks 
questions, ? mark will be deducted for each wrong answer.  However, in the case of the linked 
answer question pair, there will be negative marks only for wrong answer to the first question and no 
negative marks for wrong answer to the second question.  
10. Calculator is allowed whereas charts, graph sheets or tables are NOT allowed in the examination hall. 
11. Rough work can be done on the Question Booklet itself. Blank pages are provided at the end of the 
Question Booklet for rough work. 
12. Before the start of the examination, write your name and registration number in the space provided 
below using a black ink ballpoint pen. 
Name 
 
 
Registration Number 
EC 
       
 
 
C 
2013                                                                                                                             ELECTRONICS & COMMN. ENGG.  -  EC                                                                                                                       
 
EC-C 2/24
Q.1 to Q.25 carry one mark each. 
 
Q.1 The bit rate of a digital communication system is R kbits/s. The modulation used is 32-QAM. The 
minimum bandwidth required for ISI free transmission is  
(A) R/10 Hz (B) R/10 kHz (C)  R/5 Hz (D)  R/5 kHz 
 
Q.2 For 8085 microprocessor, the following program is executed. 
 
          MVI A, 05H; 
          MVI B, 05H; 
PTR: ADD B; 
          DCR B; 
          JNZ PTR; 
          ADI 03H; 
          HLT; 
 
At the end of program, accumulator contains 
(A) 17H (B) 20H (C) 23H  (D)  05H 
 
Q.3 Consider a delta connection of resistors and its equivalent star connection as shown below. If all 
elements of the delta connection are scaled by a factor k, k> 0, the elements of the corresponding 
star equivalent will be scaled by a factor of 
R
B
R
C
R
b
R
a
R
c
R
A
 
(A) k
2
 (B) k (C)  1/k (D) k 
 
Q.4 In the circuit shown below what is the output voltage (V
out
) if a silicon transistor Q and an ideal  
op-amp are used? 
 
+15 V
– 15 V
5V
1 k? 
V
out
+
–
Q
 
 
(A) 15 V (B) 0.7 V   
(C)  0.7 V   (D)  15 V 
 
2013                                                                                                                             ELECTRONICS & COMMN. ENGG.  -  EC                                                                                                                       
 
EC-C 3/24
Q.5 
The Bode plot of a transfer function ) (s G is shown in the figure below.  
 
Gain (dB)
 
The gain ) ) ( log 20 ( s G is 32 dB and 8 - 
dB at 1 rad/s and 10 rad/s respectively. The phase is 
negative for all ?. Then ) (s G is  
(A) 
s
8 . 39
 (B) 
2
8 . 39
s
 (C)  
s
32
  (D)  
2
32
s
 
 
Q.6 The impulse response of a system is ) ( ) ( t u t t h = . For an input , ) 1 ( - t u the output is 
(A) ) (
2
2
t u
t
 
(B) ) 1 (
) 1 (
2
- - t u
t t
 
(C) ) 1 (
) 1 (
2
2
- - t u
t
 (D) ) 1 (
1
2
2
- - t u
t
 
 
Q.7 The divergence of the vector field ˆ ˆ ˆ
x y z
A xa ya za = + +
r
is 
(A) 0 (B) 1/3 (C) 1  (D) 3  
 
Q.8 The maximum value of ?
 
until which the approximation sin? ? ˜
 
holds to within 10% error is  
(A) 10° (B) 18° (C) 50° (D) 90° 
 
Q.9 In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or 
water vapor) produces 
(A)   superior quality oxide with a higher growth rate 
(B)   inferior quality oxide with a higher growth rate 
(C)   inferior quality oxide with a lower growth rate 
(D)   superior quality oxide with a lower growth rate 
 
Q.10 In a forward biased pn junction diode, the sequence of events that best describes the mechanism of 
current flow is 
(A)   injection, and subsequent diffusion and recombination of minority carriers 
(B)   injection, and subsequent drift and generation of minority carriers 
(C)   extraction, and subsequent diffusion and generation of minority carriers 
(D)   extraction, and subsequent drift and recombination of minority carriers 
2013                                                                                                                             ELECTRONICS & COMMN. ENGG.  -  EC                                                                                                                       
 
EC-C 4/24
Q.11 Two systems with impulse responses 
1
( ) h t and 
2
( ) h t  are connected in cascade. Then the overall 
impulse response of the cascaded system is given by 
(A) product of 
1
( ) h t and 
2
( ) h t 
(B) sum of  
1
( ) h t and
2
( ) h t 
(C) convolution of  
1
( ) h t and 
2
( ) h t 
(D) subtraction of 
2
( ) h t from 
1
( ) h t 
 
Q.12 Consider a vector field ( ) A r
r
r
. The closed loop line integral A dl •
?
r r

 
can be expressed as 
(A)  ( ) A ds ?× •
??
r
r

 over the closed surface bounded by the loop 
(B)   ( ) A dv ? •
???
r

 over the closed volume bounded by the loop 
(C)   ( ) A dv ?•
???
r
 over the open volume bounded by the loop  
(D)  ( ) A ds ?× •
??
r
r
 over the open surface bounded by the loop 
 
Q.13 A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the 
first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches 
irrespective of the state of the other switch. The logic of switching of the bulb resembles 
(A) an AND gate (B) an OR gate (C) an XOR gate   (D) a NAND gate   
 
Q.14 Let 
2
p t
( ) g t e
- = , and ( ) h t is a filter matched to ( ) g t . If ( ) g t is applied as input to ( ) h t , then 
the Fourier transform of the output is 
(A) 
2
f
e
p - (B) 
2
/2 f
e
p - 
(C)  
| | f
e
p - 
(D)  
2
2 f
e
p - 
 
Q.15 The return loss of a device is found to be 20 dB. The voltage standing wave ratio (VSWR)  and 
magnitude of reflection coefficient are respectively 
(A) 1.22 and 0.1 (B) 0.81 and 0.1 (C) - 1.22 and 0.1 (D) 2.44 and 0.2 
 
Q.16 
A source  ( ) cos100
s
v t V t p =
 
has an internal impedance of (4 + j3) ?. If a purely resistive load  
connected to this source has to extract the maximum power out of the source, its value in ? should be 
(A) 3 (B) 4 (C)  5 (D) 7