## Analog Electronics 2 - Dec 2015

### Electronics & Telecomm. (Semester 4)

TOTAL MARKS: 80

TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.

(2) Attempt any **three** from the remaining questions.

(3) Assume data if required.

(4) Figures to the right indicate full marks.

### Solve Any Four:

**1 (a)** In case of CE amplifier, why does the bandwidth of amplifier decrease with increase in gain? Support the answer with relevant mathematical equation.(5 marks)
**1 (b)** Instead of single Power Supply, why we use Dual power supply biasing for differential amplifier?(5 marks)
**1 (c)** Why Efficiency of class A power Amplifier is less than class B.(5 marks)
**1 (d)** What is the drawback of current mirror circuit using MOSFET? How it is overcome?(5 marks)
**1 (e)** Why we prefer series voltage Regulator over shunt voltage Regulator? Explain in detail.(5 marks)
**2 (a)** The Parameters of transistor are V_{BE}=07 V and β=100, V_{A}=0V, Determine

a) Q point of BJT

b) Time constant associated with C_{C1} and C_{C2}

c) Lower cut-off frequency due to C_{C1} and C_{C2}.
(10 marks)
**2 (b)** For the PMOS CS amplifier, transistor parameters are V_{TP}=-2.V, Kp=1 mA/V^{2}, λ=0, Cgs=15 pf, Cgd=3pf

Determine

(a) Equivalent Miller capacitance

b) upper 3dB frequency
(10 marks)
**3 (a)** For the given circuit, Determine

i) Differential mode gain Ad

ii) Common mode gain Ac

iii) CMRR

For BJT β=100 V_{BE}=0.7V, V_{A}=100V.
(10 marks)
**3 (b)** Draw and explain the working of class A power amplifier (Transformer coupled). Derive the expression for efficiency.(10 marks)
**4 (a)** Draw and explain current mirror circuit using MOSFET, for the given circuit determine the value of l_{ref} and l_{0}
(10 marks)
**4 (b)** Draw the circuit diagram of Darlington pair using BJT, and derive the expression for Av, Ai, Zi and Zd.(10 marks)
**5 (a)** For the given circuit, derive the equation for voltage gain A_{f} and find V_{o} for given cor

Vi |
Vo |
Ri |
Rf |

+1 VDC | ? | IK | 10k |

+1 VDC | ? | IK | 100K |

+1 VDC | ? | IK | 1M |

**5 (b)**Draw the circuit diagram of MOS differential amplifier and derive the expression for A

_{d}, A

_{cm}and CMRR.(10 marks)

### Write short note on (Attempt any Four:)

**6 (a)** High pass and low pass filter using OPAMP(5 marks)
**6 (b)** Cascode amplifier using BJT(5 marks)
**6 (c)** Widlar current source using MOSFET.(5 marks)
**6 (d)** Transistor shunt voltage regulator.(5 marks)
**6 (e)** High frequency hybrid-π model of BJT.(5 marks)