GATE 2009 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. In the following Astable Multivibrator circuit, which properties of V_o(t) depend on R₂ ?

a. Only the frequency
b. Only the amplitude
c. Both the amplitude and the frequency
d. Neither the amplitude nor the frequency

Answer:A

Solution: https://www.youtube.com/watch?v=CNrhstw1lQI


2. In the circuit shown below, the OP-AMP is ideal, the transistor has V_BE = 0.6 volts and β = 150. Decide whether the feedback in the circuit is positive or negative and determine the voltage V at the output of the OP-AMP.

a. Positive feedback, V = 10 Volts
b. Positive feedback, V = 0 Volts
c. Negative feedback, V = 5 Volts
d. Negative feedback, V = 2 Volts

Answer:D

Solution: https://www.youtube.com/watch?v=H6FpEgr7ZYI


3. A small signal source Vi(t) = Acos20t + Bsin10⁶t is applied to a transistor amplifier as shown below. The transistor has β = 150 and h_ie = 3 KΩ. Which expression best approximate V_o(t).

a. V_o(t) = - 1500 (Acos20t + Bsin10⁶t)
b. V_o(t) = - 150 (Acos20t + Bsin10⁶t)
c. V_o(t) = - 1500 (Bsin10⁶t)
d. V_o(t) = - 150 (Bsin10⁶t)

Answer:D

Solution: https://www.youtube.com/watch?v=C-1mKYDJhY4