GATE 1988 ECE Analog Circuits (Analog Electronics) - Video Solutions

1. The OP-AMP shown in figure below is ideal and R = (L/C)^1/2. The phase angle between Vo and Vi at ω = 1/(LC)^1/2 is

a. π/2
b. π
c. 3π/2
d. 2π

Answer: C

Solution : https://www.youtube.com/watch?v=FKQ_eoFq0z8


2. The quiescent collector current I_C, of a transistor is increased by changing resistances. As a result
a. g_m will not be effected
b. g_m will decrease
c. g_m will increase
d. g_m will increase or decrease depending upon bias stability

Answer: C

Solution : https://www.youtube.com/watch?v=gFs1ZE7V53g


3. Each transistor in the Darlington pair shown below has h_FE = 100. The overall h_FE of the composite transistor, neglecting the leakage currents is

a. 10000
b. 10001
c. 10100
d. 10200

Answer: C

Solution : https://www.youtube.com/watch?v=RQH1T3W2_9Q


4. The amplifier circuit shown below uses a composite transistor of a MOSFET and BIPOLAR in cascade. All capacitances are large. g_m of the MOSFET is 2 mA/V, and h_fe of the BIPOLAR is 99. The overall Transconductance g_m of the composite transistor is

a. 198 mA/V
b. 9.9 mA/V
c. 4.95 mA/V
d. 1.98 mA/V

Answer: D

Solution : https://www.youtube.com/watch?v=wAU2oCxn8jY


5. The transistor in the amplifier shown below has following parameters: h_fe = 100, h_ie = 2 kΩ, h_re = 0, h_oe = 0.05 mhos. All capacitors are very large. The output impedance is

a. 20 kΩ
b. 16 kΩ
c. 5 kΩ
d. 4 kΩ

Answer: D

Solution : https://www.youtube.com/watch?v=ho6X62lwwdg

GATE 1988 Video Solutions on Digital Circuits

1. For the circuit shown below, the output F is given by

Answer:B

Solution : https://www.youtube.com/watch?v=PvXtxYyx0VI


2. Minimum number of 2 input NAND gates required to implement the function given below is

a. 3
b. 4
c. 5
d. 6

Answer:B

Solution : https://www.youtube.com/watch?v=pLnpil_Lp6I


3. The circuit given below is a

a. JK flip flop
b. Johnson counter
c. RS latch
d. None of the above

Answer:C

Solution : https://www.youtube.com/watch?v=vgY4u6Yqfqo

GATE 1988 Video Solutions on EDC (Electronic Devices and Circuits)

1.       For a PN junction, match the type of breakdown with phenomenon

i.         Avalanche breakdown

ii.       Zener breakdown

iii.      Punch through

a.       Collision of carriers with crystal ions

b.      Early effect

c.       Rupture of covalent bond due to strong electric field

Answer:i-a, ii-c, iii-b

                 Solution :https://www.youtube.com/watch?v=EN4l13yKuqM

2.       In the circuit shown below, the current voltage relationship when D₁ and D₂ are identical is given by  (assume Germanium diodes)

Answer:B

                 Solution : https://www.youtube.com/watch?v=TKrqrKu90i8

3.       In an N-channel JFET, V_GS is held constant. V_DS is less than the breakdown voltage. As V_DS is increased…(Assume ‘S’ as conducting cross sectional area of the channel and ‘J’ as channel current density)

a.       ‘S’ increases and ‘J’ increases 

b.      ‘S’ decreases and ‘J’ decreases

c.       ‘S’ decreases and ‘J’ increases

d.      ‘S’ increases and ‘J’ decreases

Answer:C

                 Solution : https://www.youtube.com/watch?v=5wE7t_1k180

4.       In MOSFET devices, the N-channel type is better than the P-channel type in the following respects

a.       It has better noise immunity

b.      It is faster

c.       It is TTL compatible

d.      It has better drive capability

Answer:D

                 Solution : https://www.youtube.com/watch?v=i0tBM4SR3ug