DipIETE – ET (NEW SCHEME)   –   Code: DE56

 

Subject: ANALOG ELECTRONICS

Flowchart: Alternate Process: JUNE 2010 Time: 3 Hours                                                                                                     Max. Marks: 100

 

 

NOTE: There are 9 Questions in all.

·      Question 1 is compulsory and carries 20 marks. Answer to Q.1 must be written in the space provided for it in the answer book supplied and nowhere else.

·      Out of the remaining EIGHT Questions, answer any FIVE Questions. Each question carries 16 marks.

·      Any required data not explicitly given, may be suitably assumed and stated.

 

Q.1       Choose the correct or the best alternative in the following:                                  (210)

       

a.    Most commonly used technique for preparing single crystal silicon from polycrystalline silicon is by __________.

 

                  (A) Laplace method                              (B) Heaviside method

                  (C) Czochralski method                        (D) None of the above

 

             b. Diffusion of impurities takes place at temperature of _____________.

 

                  (A)                                               (B)                                                                          

                  (C)                                               (D)

 

             c.  Maximum current gain is obtained using __________.

 

                  (A) C B Configuration                          (B) C E Configuration

                  (C) C C Configuration                          (D) None of the above

 

             d.  Which device is thermally more stable?

 

                  (A) FET                                               (B) BJT

                  (C) PN Diode                                      (D) Zener diode

 

             e.  One lumen is how many milliwatts?

 

                  (A) 2.136                                             (B) 1.496

                  (C) 0.234                                             (D) 5.136                                                             

 

             f.   The reflected load (rL) in a transformer coupled class A power amplifier is

 

                  (A)                                     (B) RL

                  (C) 2RL                                                (D)

 

             g. Theoretical conversion power efficiency of class B power amplifier is

 

                  (A) 78.6%                                            (B) 50%

                  (C) 25%                                               (D) 94.6%

 

h.   The input bias current of 741 bipolar op-amp is approximately  

 

(A)  10 nA                                            (B) 50 pA

                  (C) 500 nA                                          (D) 1 A

 

             i.   Astable multivibrator has

 

                  (A) Two stable states                            (B) One stable state

                  (C) No stable state                               (D) Three stable state

 

             j.   RC oscillators are used at

 

                  (A) Audio frequencies                           (B) Radio frequencies

                  (C) Video frequencies                           (D) All frequencies

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

 

  Q.2     a.   Explain briefly classification of integrated circuits.                                                (4)

                  

             b.   Explain two methods of isolation techniques used fabrication of integrated circuits.              (6)

 

             c.   Distinguish between diffused and pinched silicon with suitable diagrams               (6)

 

  Q.3     a.   Derive expressions for input impedance, output impedance and voltage gain of CE transistor amplifier with unbypassed emitter Resistor (Re). Draw its equivalent ‘h’ parameter.                                  (9)

 
 
             b.   The transistor parameters for the CC circuit shown in Fig.1 are transistor hic=2.1 k, hfc =76, hib = 27.60. (i) Calculate the circuit input and output impedance with RL not connected.(ii) calculate Zi and AV with RL connected.

                                                                                                                                             (7)

 

 

 

 

 

 

 

 

 

 

 

 

 

  Q.4     a.   With neat diagram explain the working of depletion-enhancement MOSFET                                   (10)

 

             b.   Compare the performance of the three basic JFET circuits in term of the difference between ID(max) and ID(min)                                                                                                                         (6)

 

Q.5      a.   With a neat diagram explain the working of a transformer coupled class A power amplifier and obtain an expression for theoretical maximum power conversion efficiency.                                        (10)

       

             b.   Explain the construction and operation of light emitting diode (LED).                   (6)

 

  Q.6     a.   Draw the circuit of op amp differential amplifier and explain. Obtain expression for output voltage.                                                             (8)

       

             b.   For the  Fig.2  shown below let R1 =5 k,0 Rf = 20 kand   A load resistor of 5 k is connected at the output. Calculate (i)                   (ii) ACL (iii) the load current iL.                       (4)
 
 

 

 

 

 

 

 

 

 

 

 

 


            

 

 

 

 

             c.   Calculate the maximum frequency of undistorted sine wave that can be obtained at the output of an op amp which has a slew rate of 1 V/ sec when input is a sine wave with a peak of 10 V. (4)

       

  Q.7     a.   Draw the circuit of a full wave precision rectifier, explain with suitable waveforms.               (8)

 

             b.   Draw the circuit of an instrumentation amplifier using three Op-amps.  Derive expression for output voltage.                                                                                                                         (8)

 

Q.8       a.                                                              Draw the circuit of a monostable multivibrator using 555 timer, and derive the expression for pulse period.                                                               (9)

 

             b.   Draw the circuit of an inverting Schmitt trigger and calculate VUT and VLT if R1 = 50 k, R2 = 1 k, Vref = 0 and Vi = 1 Volt peak to peak sine wave and saturation voltages  14 V. Draw input, output waveform and draw the transfer characteristics.                                                                  (7)

 

  Q.9     a.   With a diagram explain the working of successive approximation ADC.             (10)

            

             b.   Design a voltage regulator using 723 to get an output voltage of 3 V. Draw the circuit.                    (6)