GATE 2004 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. An ideal OP-AMP is an ideal
a. Voltage Controlled Current Source
b. Voltage Controlled Voltage Source
c. Current Controlled Current Source
d. Current Controlled Voltage Source

Answer: B

Solution: https://www.youtube.com/watch?v=-3pE3zjlc-I


2. Voltage series feedback (also called series-shunt feedback) results in
a. Increase in both input and output impedances
b. Decrease in both input and output impedances
c. Increase in input impedance and decrease in output impedance
d. Decrease in input impedance and increase in output impedance

Answer: C

Solution: https://www.youtube.com/watch?v=W1PMTIiCpuU


3. The circuit in the figure is a

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

Answer: A

Solution: https://www.youtube.com/watch?v=hUwaNK0aINo


4. A bipolar transistor is operating in the active region with a collector current of 1 mA. Assuming that the β of the transistor is 100 and the thermal voltage (V_T) is 25 mV. The Transconductance (g_m) and the input resistance (r_π) of the transistor in the common emitter configuration are
a. g_m = 25 mA/V and r_π = 15.625 KΩ
b. g_m = 40 mA/V and r_π = 4.0 KΩ
c. g_m = 25 mA/V and r_π = 2.5 KΩ
d. g_m = 40 mA/V and r_π = 2.5 KΩ

Answer: D

Solution: https://www.youtube.com/watch?v=cK0KRkqCWVw


5. the value of capacitor C required for sinusoidal oscillations of frequency 1 kHz in the circuit of the figure is

Answer: A

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


6. in the OP-AMP circuit given in the figure, the load current i_L is

a. – V_S / R₂
b. V_S / R₂
c. – V_S / R_L
d. V_S / R₁

Answer: A

Solution: https://www.youtube.com/watch?v=TxVYCU-8ejQ


7. In the full wave rectifier using two ideal diodes, V_dc and V_m are the dc and peak values of the voltage respectively across a resistive load. If PIV is the peak inverse voltage of the diode, then the appropriate relationships for this rectifier are

Answer: B

Solution: https://www.youtube.com/watch?v=bN5s61Q90RE

GATE 2005 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. The effect of current shunt feedback in an amplifier is to
a. Increase the input resistance and decrease the output resistance.
b. Increase both input and output resistances
c. Decrease both input and output resistances
d. Decreases the input resistance and increase the output resistance

Answer: D

Solution: https://www.youtube.com/watch?v=ZZ6rItV_wj8


2. The input resistance R_i of the amplifier shown in figure is

a. 30/4 KΩ
b. 10 KΩ
c. 40 KΩ
d. Infinite

Answer: B

Solution: https://www.youtube.com/watch?v=N7D9lXz25dU


3. The cascode amplifier is a multistage configuration of
a. CC – CB
b. CE – CB
c. CB – CC
d. CE – CC

Answer: B

Solution: https://www.youtube.com/watch?v=srt3MdOny5g


4. A square pulse of 3 volts amplitude is applied to RC circuit shown in figure. The capacitor is initially uncharged. The output voltage V_o at time t = 2 sec is

a. 3 volts
b.– 3 volts
c. 4 volts
d. – 4 volts

Answer:B

Solution:


5. For an NPN transistor connected as shown in figure, V_BE = 0.7 volts. Given that reverse saturation current of the junction at room temperature 300^oK is 10^-13 amp, the emitter current is

a. 30 mA
b. 39 mA
c. 49 mA
d. 20 mA

Answer:C

Solution: https://www.youtube.com/watch?v=3HVbE9qCcH8


6. The voltage e_o indicated in figure has been measured by an ideal voltmeter, which of the following can be calculated?

a. Bias current of the inverting input only
b. Bias current of the inverting and non-inverting inputs only
c. Input offset current only
d. Both the bias currents and the input offset current.

Answer:C

Solution: https://www.youtube.com/watch?v=OuIncy3Iz-w


7. The OP-AMP circuit shown in figure is a filter. The type of filter and its cut-off frequency are respectively.

a. High pass, 1000 rad/sec
b. Low pass, 1000 rad/sec
c. High pass, 10000 rad/sec
d. Low pass, 10000 rad/sec

Answer:A

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


8. In the differential amplifier shown in figure, a large value of R_E

a. Increases both the differential and common mode gains
b. Increases the common mode gain only
c. Decreases the differential mode gain only
d. Decreases the common mode gain only

Answer:D

Solution: https://www.youtube.com/watch?v=YH9E2xVqdv0


9. The circuit using a BJT with β = 50 and V_BE = 0.7 volts is shown in figure. The base current I_B and the collector voltage V_C are respectively.

a. 43 µA and 11.4 volts
b. 40 µA and 16 volts
c. 45 µA and 11 volts
d. 50 µA and 10 volts

Answer:B

Solution: https://www.youtube.com/watch?v=W8VHHTLp6Kg


10. Given the ideal operational amplifier circuit shown in figure indicate the correct transfer characteristics assuming ideal diodes with zero cut-in voltage.

Answer:B

Solution: https://www.youtube.com/watch?v=q_6bzIBuW7A


Common Data Questions for 11, 12 and 13:
Given r_d = 20 KΩ, I_DSS = 10 mA, V_P = - 8 volts.

11. Z_i and Z_o of the circuit are respectively
a. 2 MΩ and 2 KΩ
b. 2 MΩ and 20/11 KΩ
c. Infinity and 2 KΩ
d. Infinity and 20/11 KΩ

Answer:B

12. I_D and V_DS under DC conditions are respectively
a. 5.625 mA and 8.75 Volts
b. 7.50 mA and 5.0 Volts
c. 4.50 mA and 11.0 Volts
d. 6.25 mA and 7.5 Volts

Answer:A

13. Transconductance in milli-siemens (mS) and the voltage gain of the amplifier are
a. 1.875 mS and 3.41
b. 1.875 mS and – 3.41
c. 3.30 mS and – 6
d. 3.30 mS and 6

Answer:B

Solution(11, 12, 13): https://www.youtube.com/watch?v=3EaSdIyGqME

GATE 2006 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. The input impedance(Z_i) and output impedance (Z_o) of an ideal Transconductance (voltage controlled current source) amplifier are
a. Z_i = 0, Z_o = 0
b. Z_i = 0, Z_o = ∞
c. Z_i = ∞, Z_o = 0
d. Z_i = ∞, Z_o = ∞

Answer:D

Solution: https://www.youtube.com/watch?v=ZF6_tDjeD-w


2. For the circuit shown in the following figure, the capacitor C is initially uncharged. At t = 0, the switch S is closed. The voltage V_C across the capacitor at t = 1 ms is _____. Assume the OP – AMP is supplied with ± 15 volts.

a. 0 volts
b. 6.3 volts
c. 9.45 volts
d. 10 volts

Answer:D

Solution: https://www.youtube.com/watch?v=XbVKE5nEOPI


Common Data for Questions (3, 4 and 5):
In the transistor amplifier circuit shown in the figure below, the transistor has the following parameters: β_DC = 60, V_BE = 0.7 volts, h_ie -> ∞, h_oe -> ∞. The capacitance C_C can be assumed to be infinite.

3. Under the DC conditions, the collector to emitter voltage drop is
a. 4.8 volts
b. 5.3 volts
c. 6.0 volts
d. 6.6 volts

Answer: C

4. If β_DC is increased by 10%, the collector to emitter voltage drop
a. Increases by less than or equal to 10%
b. Decreases by less than or equal to 10%
c. Increases by more than 10%
d. Decreases by more than 10%

Answer: B

5. The small signal gain of the amplifier V_o/V_s is
a. – 10
b. – 5.3
c. + 5.3
d. + 10

Answer:A

Solution(3, 4, 5): https://www.youtube.com/watch?v=qdpEHlqob00


Statement for Linked Answer Questions (6 and 7):
A regulated power supply shown in the figure below has an unregulated input of 15 volts and generates a regulated output V_out. Use the component values shown in the figure.

6. The power dissipation across the transistor Q₁ shown in the figure is
a. 4.8 volts
b. 5.0 volts
c. 5.4 volts
d. 6.0 volts

Answer:D

7. If the unregulated voltage increases by 20%, then power dissipation across the transistor Q₁
a. Increases by 20%
b. Increases by 50%
c. Remains unchanged
d. Decreases by 20%

Answer:B

Solution(6 & 7): https://www.youtube.com/watch?v=_fx1s9uTcCw

GATE 2007 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. In a Transconductance amplifier, it is desirable to have
a. A large input resistance and a large output resistance
b. A large input resistance and a small output resistance
c. A small input resistance and a large output resistance
d. A small input resistance and a small output resistance

Answer:A

Solution: https://www.youtube.com/watch?v=XdHNm2Ly-Kc


2. For the OP-AMP circuit shown in the figure, V_o is

a. – 2 volts
b. – 1 volts
c. – 0.5 volts
d. + 0.5 volts

Answer:C

Solution: https://www.youtube.com/watch?v=GNXEesKW7VQ


3. In the OP-AMP circuit shown, assume that the diode current follows the equation I = I_Sexp(V/V_T). For V_i = 2 Volts, V_o = V₀₁, and for V_i = 4 Volts, V_o = V₀₂. The relationship between V₀₁ and V₀₂ is

a. V₀₂ = √2 V₀₁
b. V₀₂ = e² V₀₁
c. V₀₂ = V₀₁ ln2
d. V₀₂ - V₀₁ = V_T ln2

Answer: D

Solution: https://www.youtube.com/watch?v=_FEUmzL53hg


Statement for Linked Answer Questions
Consider the OP-AMP circuit shown in the figure.

4. The Transfer function V_o(s)/ V_i(s) is

Answer:A

5. If V_i = V₁ sin(ωt) and V_o = V₂ sin(ωt+ø), then the minimum and maximum values of ø (in radians) are respectively
a. – π/2 and π/2
b. 0 and π/2
c. – π and 0
d. – π/2 and 0

Answer: C

Solution(4 & 5): https://www.youtube.com/watch?v=5BVus7UsCas