**Set – 1 (15th February 2014 (Forenoon))**

1. In the figure, assume that the forward voltage drops to the PN diode D

_{1}and Schottky diode D

_{2}are 0.7 volts and 0.3 volts respectively. If ON denotes conducting state of the diode and OFF denotes the non conducting state of the diode, then in the circuit,

a. Both are ON

b. D

_{1}is ON and D

_{2}is OFF

c. Both are OFF

d. D

_{1}is OFF and D

_{2}is ON

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

2. A good current buffer has

a. Low input impedance and low output impedance

b. Low input impedance and high output impedance

c. high input impedance and low output impedance

d. high input impedance and high output impedance

**Solution :**https://www.youtube.com/watch?v=vdYmByP9zYY

3. In the ac equivalent circuit shown in the figure, if i

_{in}is the input current and R

_{F}is very large, then the type of feedback is

a. Voltage – Voltage feedback

b. Voltage – Current feedback

c. Current – Voltage feedback

d. Current – Current feedback

**Solution :**https://www.youtube.com/watch?v=otvYW4oudRg

4. In the low pass filter shown in the figure, for a cutoff frequency of 5 KHz, the value of R

_{2}(in KΩ) is ……..

**Solution :**https://www.youtube.com/watch?v=BjcHUWQA4TQ

5. A BJT is biased in forward active mode. Assume V

_{BE}= 0.7 volts, KT/q = 25 mV and reverse saturation current I

_{S}= 10

^{-13}Amp. The Transconductance of the BJT (in mA/volt) is…..

**Solution :**https://www.youtube.com/watch?v=nAh0aTdVp84

6. In the voltage regulator circuit shown in the figure, the Op-Amp is ideal. The BJT has V

_{BE}= 0.7 volts, and β = 100, and the zener voltage is 4.7 volts. For a regulated output of 9 volts, the value of R (in Ω) is ……..

**Solution :**https://www.youtube.com/watch?v=B5rropdO8jA

7. In the circuit shown, the Op-Amp has finite input resistance, infinite voltage gain and zero input offset voltage. The output voltage V

_{out}is …….

a. – I

_{2}(R

_{1}+ R

_{2})

b. I

_{2}R

_{2}

c. I

_{1}R

_{2}

d. – I

_{1}(R

_{1}+ R

_{2})

**Solution :**https://www.youtube.com/watch?v=DAEuj8Z-ncY

8. For the amplifier shown in the figure, the BJT parameters are V

_{BE}= 0.7 volts, β = 200, and thermal voltage V

_{T}= 25 mV. The voltage gain (v

_{o}/v

_{i}) of the amplifier is ……..

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

**SET – 2 (15th February 2014 (Afternoon))**

1. The diode in the circuit shown, if V

_{on}= 0.7 volts but is ideal otherwise. If V

_{i}= 5 sin(ωt) volts, the minimum and maximum values of V

_{o}(in volts) are, respectively,

a. -5 and 2.7

b. 2.7 and 5

c. -5 and 3.85

d. 1.3 and 5

**Solution :**https://www.youtube.com/watch?v=VNI1bsbW2i8

2. The feedback topology in the amplifier circuit (the base bias circuit is not shown for simplicity) in the figure is

a. Voltage – Shunt feedback

b. Current – Series feedback

c. Current – Shunt feedback

d. Voltage – Series feedback

**Solution :**https://www.youtube.com/watch?v=MNduRhMC6zk

3. In the differential amplifier shown in the figure, the magnitude of the common mode and differential mode gains are A

_{cm}and A

_{d}, respectively. If the resistance R

_{E}is increased, then

a. A

_{cm}increases

b. Common mode rejection ratio increases

c. A

_{d}increases

d. Common mode rejection ratio decreases

**Solution :**https://www.youtube.com/watch?v=AhxODnKBU5Y

4. A cascade connection of two voltage amplifiers A1 and A2 is shown in the figure. The open loop gain A

_{vo}, input resistance R

_{in}, and output resistance R

_{o}for A1 and A2 are as follows:

A1 : A

_{vo}= 10, R

_{in}= 10 KΩ, R

_{o}= 1 KΩ

A2 : A

_{vo}= 5, R

_{in}= 5 KΩ, R

_{o}= 200 Ω

The approximate overall voltage gain V

_{out}/ V

_{in}is …………….

**Solution :**https://www.youtube.com/watch?v=ijiC9w_XNuw

**SET – 3 (16th February 2014 (Forenoon))**

1. In the circuit shown, the PNP transistor has |V

_{BE}| = 0.7 volts and β = 50. Assume that R

_{B}= 100 KΩ. For V

_{o}to be 5 volts, the value of R

_{C}(in KΩ) is ……..

**Solution :**https://www.youtube.com/watch?v=ohf5m4r0gzs

2. The desirable characteristics of a Transconductance amplifier are

a. High input resistance and High output resistance

b. High input resistance and Low output resistance

c. Low input resistance and High output resistance

d. Low input resistance and Low output resistance

**Solution :**https://www.youtube.com/watch?v=1RsZ43lyRhs

3. The figure shows a half wave rectifier. The diode D is ideal. The average steady state current (in Amperes) through the diode is approximately…………

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

4. Assuming that the Op-Amp in the circuit is ideal, then the output voltage is

**Solution :**https://www.youtube.com/watch?v=Q7DUP4Rz58o

5. In the circuit shown, the silicon BJT has β = 50. Assume V

_{BE}= 0.7 volts and V

_{CEsat}= 0.2 volts. Which one of the following statements is correct?

a. For R

_{C}= 1 kΩ, the BJT operates in the saturation region

b. For R

_{C}= 3 kΩ, the BJT operates in the saturation region

c. For R

_{C}= 20 kΩ, the BJT operates in the cutoff region

d. For R

_{C}= 20 kΩ, the BJT operates in the linear region

**Solution :**https://www.youtube.com/watch?v=zd_NFD2CN8E

**SET - 4 (16th February 2014 (Afternoon))**

1. If the emitter resistance in a common emitter voltage amplifier is not bypassed, it will

a. Reduce both the voltage gain and the input impedance

b. Reduce the voltage gain and increase the input impedance

c. Increase the voltage gain and reduce the input impedance

d. Increase both the voltage gain and the input impedance

**Solution :**https://www.youtube.com/watch?v=4YjclPDw5lM

2. Consider two BJTs biased at the same collector current with area A

_{1}= 0.2 µm x 0.2 µm and A

_{2}= 300 µm x 300 µm. assuming that all other device parameters are identical, KT/q = 26 mV, the intrinsic carrier concentration is 1 x 10

^{10}cm

^{-3}, and q = 1.6 x 10

^{-19}C, the difference between the base emitter voltages (in mV) of the two BJTs (i.e. V

_{BE1}– V

_{BE2}) is …………….

**Solution :**https://www.youtube.com/watch?v=R-GogUWvN74

3. A BJT in a common base configuration is used to amplify a signal received by a 50Ω antenna. Assume KT/q = 25 mV, the value of collector bias current (in mA) required to match the input impedance of the amplifier to the impedance of the antenna is ………..

**Solution :**https://www.youtube.com/watch?v=HBjqJb91WbE

4. Two silicon diodes, with a forward voltage drop of 0.7 volts, are used in the circuit shown in the figure. The range of input voltage Vi for which the output voltage Vo = Vi, is

a. -0.3 volts < Vi < 1.3 volts

b. -0.3 volts < Vi < 2 volts

c. -1.0 volts < Vi < 2.0 volts

d. -1.7 volts < Vi < 2.7 volts

**Solution :**https://www.youtube.com/watch?v=6GsjQs9DKbU

5. The circuit represents

a. A band pass filter

b. A voltage controlled oscillator

c. An Amplitude modulator

d. A monostable multivibrator

**Solution :**https://www.youtube.com/watch?v=oi_nPP2yd4k

6. Consider the common collector amplifier in the figure (bias circuitry ensures that the transistor operates in forward active region, but has been omitted for simplicity). Let I

_{C}be the collector current, V

_{BE}be the base emitter voltage and V

_{T}be the thermal voltage. Also, g

_{m}and r

_{o}are the small signal Transconductance and output resistance of the transistor, respectively. Which one of the following conditions ensures a nearly constant small signal voltage gain for a wide range of values of R

_{E}?

**Solution :**https://www.youtube.com/watch?v=Xur5bWVoR10

7. For the common collector amplifier shown in the figure, the BJT has high β, negligible V

_{CEsat}and V

_{BE}= 0.7 volts. The maximum undistorted peak to peak output voltage V

_{o}(in volts) is ………

**Solution :**https://www.youtube.com/watch?v=LsXNjgHVeK0