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