Question Paper: Electronic Devices and Circuits 1 Question Paper - May 18 - Electronics And Telecomm (Semester 3) - Mumbai University (MU)
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## Electronic Devices and Circuits 1 - May 18

### Electronics And Telecomm (Semester 3)

Total marks: 80
Total time: 3 Hours
INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.

Q1) Attempt any five questions

1(a) Prove that for a JFET the gate-source bias for zero temperature drift of drain current is at | Vp | = - 0.63 volts.
(5 marks) 00

1(b) Explain the hybrid pi model of BJT.
(5 marks) 3608

1(c) Explain Zener as voltage regulator.
(5 marks) 2024

1(d) Consider a BJT has parameters $fT =500MHz$ at $IC = 1mA$, $β = 100 and Cμ = 0.3pF$. Calculate bandwidth of $fβ$ and capacitance $Cπ$ of a BJT.
(5 marks) 00

1(e) Draw and explain small signal model of a diode.
(5 marks) 1721

1(f) Why should RC be as large as possible in the design of CE amplifier?
(5 marks) 00

2(a) Design a voltage divider bias network using a supply of 24 V, a transistor with $β=110$ and an operating point of $I_{CQ} = 4 mA$ and $V_{CEQ} = 8V$. Assume

$$V_E = \frac{1}{8} V_{CC}$$

(10 marks) 00

2(b) Explain the fabrication steps of passive elements
(5 marks) 3770

2(c) What are the important JFET parameters and define it from characteristics.
(5 marks) 2279

3(a) Design the resistors of a single stage CS amplifier for audio frequency with BFW11 with $I_{DS} = (3.3 \pm 0 .6 ) mA$ and $| A_V | = 12.$
(5 marks) 00

3(b) Draw CS JFET amplifier with self bias circuit and derive the expression for voltage gain input impedance and output impedance.
(5 marks) 00

4(a) Draw small signal hybrid parameter equivalent circuit for CE amplifier and define the same. What are the advantages of h parameters?
(5 marks) 2282

4(b) For the circuit shown below in Fig.4b, the transistor parameters are $V_{BE(on)} = 0.7 V$, $β = 200$ and $V_A = \infty$.

• i) Derive the expression for lower cut-off frequency (or time constant) due to input coupling capacitor.
• ii) Determine lower cut-off frequency and midband voltage gain.

(5 marks) 00

5(a) Design an L section LC filter with full wave rectifier to meet the following specifications: The DC output voltage $V_{DC} = 220 V$, deliver $I_L = (70 \pm 20) mA$ to the resistive load and the required ripple factor is 0.04.
(5 marks) 3528

5(b) For the circuit shown below in Fig.5(b), the transistor parameters are $V_{BE(on)} = 0.7 V$, $β = 100$ and $V_A = \infty$. Determine Zi, Zo and Av.

(5 marks) 00

Q6) Short notes on: (Attempt any four)

6(a) BJT high frequency equivalent circuit
(5 marks) 00

6(b) Types of resistors and capacitors
(5 marks) 00

6(c) Stability factors of various biasing techniques of BJT
(5 marks) 00

6(d) Different types of filters
(5 marks) 3771

6(e) Comparison of BJT CE and JFET CS amplifier
(5 marks) 3772