GATE 2008 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. Consider the following circuit using an ideal OP-AMP. The I-V characteristic of the diode is described by the relation I = I_o(exp(V/V_T) - 1), where VT = 25 mV, I_o = 1 µA and V is the voltage across the diode(taken as positive for forward bias). For an input voltage V_i = - 1 volts, the output voltage V_o is

a. 0 volts
b. 0.1 volts
c. 0.7 volts
d. 1.1 volts

Answer:B

Solution: https://www.youtube.com/watch?v=Hm-AQGstHH0


2. The OP-AMP circuit shown below represents a

a. High pass filter
b. Low pass filter
c. Band pass filter
d. Band reject filter

Answer:B

Solution: https://www.youtube.com/watch?v=iNclgQhX8gs


3. Consider the schmitt trigger circuit shown below.

A triangular wave which goes from –12 volts to +12 volts is applied to the inverting input of OP-AMP. Assume that the output of the OP-AMP swings from +15 volts to –15 volts. The voltage at the non-inverting input switches between
a. – 12 volts and +12 volts
b. – 7.5 volts and +7.5 volts
c. – 5 volts and +5 volts
d. 0 volts and +5 volts

Answer: C

Solution: https://www.youtube.com/watch?v=U1PM8Q0IT0o


Statement for Linked Answer Question:
In the following transistor circuit, V_BE = 0.7 volts, r_e = 25 mV/I_E, β and all the capacitances are very large.

4. The value of DC current I_E is
a. 1 mA
b. 2 mA
c. 5 mA
d. 10 mA

Answer:A

5. The mid-band voltage gain of the amplifier is approximately
a. – 180
b. – 120
c. – 90
d. – 60

Answer:D

Solution(4 & 5): https://www.youtube.com/watch?v=eX0es1gFdW4