GATE 2010 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. The amplifier circuit shown below uses a silicon transistor. The capacitors C_C and C_E can be assumed to be short at signal frequency and effect of output resistance r_o can be ignored. If C_E is disconnected from the circuit, which one of the following statements is TRUE.

a. The input resistance R_i increases and magnitude of voltage gain A_V decreases
b. The input resistance R_i decreases and magnitude of voltage gain A_V increases
c. The input resistance R_i decreases and magnitude of voltage gain A_V decreases
d. The input resistance R_i increases and magnitude of voltage gain A_V increases

Answer:A

Solution: https://www.youtube.com/watch?v=E48_Y4CYKIU


2. In the silicon BJT circuit shown below, assume that the emitter area of transistor Q₁ is half that of transistor Q₂. The value of current I_o is approximately

a. 0.5 mA
b. 2 mA
c. 9.3 mA
d. 15 mA

Answer:B

Solution: https://www.youtube.com/watch?v=jWdra3gmHK0


3. Assuming the OP-AMP is ideal, the voltage gain of the amplifier shown below is

a. - R₂/R₁
b. - R₃/R₁
c. - (R₂ || R₃) / R₁
d. - (R₂ + R₃)/R₁

Answer:A

Solution: https://www.youtube.com/watch?v=-GMfvkT72y0


4. The transfer characteristic for the precision rectifier circuit shown below is (Assume ideal OP-AMP and Practical Diodes)

Answer:B

Solution: https://www.youtube.com/watch?v=K2Rp0dv6Ll0


Common Data Questions:
Consider the common emitter amplifier shown below with the following circuit parameters.
β = 100, g_m = 0.3861 A/V, r_o = 259 Ω, R_S = 1 KΩ, R_B = 93 KΩ, R_C = 250 Ω, R_L = 1 KΩ, C₁ = ∞ and C₂ = 4.7 µF.

5. The resistance seen by the source V_S is
a. 258 Ω
b. 1258 Ω
c. 93 KΩ
d. ∞

Answer:B

6. The lower cutoff frequency due to C₂ is
a. 33.9 Hz
b. 27.1 Hz
c. 13.6 Hz
d. 16.9 Hz

Answer:B

Solution: https://www.youtube.com/watch?v=FdpAV2BR7Fc