DipIETE – ET (OLD SCHEME)

Flowchart: Alternate Process: JUNE 2010
 


Code: DE08                                                                          Subject: ANALOG ELECTRONICS

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.       The silicon transistors are more widely used than germanium transistor     because of ________.

 

(A)  smaller leakage current                

(B)  better ability to dissipate heat

(C)   smaller depletion layers                

(D)  largest current carrying capacity                                                                                

       

             b.   The biasing circuit which gives best stability to the Q point is ________. 

 

(A)    base resistor biasing

(B)    feedback resistor biasing

(C)    potential divider biasing 

(D)    emitter resistor biasing

                                                                                                                       

             c.   The maximum efficiency of a class B amplifier is __________.

                  

(A)    50 %                                            (B)  78.5 %

(C)  35 %                                            (D)  100  %.

 

             d.   The Negative feedback in an amplifier ___________. 

 

(A)  increase the voltage gain               (B) decrease the voltage gain

(C)  stabilises the voltage gain              (D) a and c both    

 

             e.   The type of feedback that is used in oscillators is _________.

                  

(A)     positive feedback                         (B)  negative feedback

(C)  no feedback                                 (D)  none of the above

 

             f.    Q factor of a resonance circuit is given by ___________.

 

(A)                                    (B)   

(C)                              (D) 

 

 

 

                  

             g.   The gain of an inverting amplifier is given by _________.

 

(A)      –R1/RF                                      (B)  R1/RF

(C)   –RF/R1                                       (D)  RF/R1

 

             h.   In the clamper circuits the output waveform level is ________.

 

(A)    eliminated 

(B)    shifted

(C)    Both (A) and (B)                           

                   (D)  None of these

 

             i.    The ideal op-amp input impedance is ________.

 

(A)   zero                                              (B)  infinite 

(C) unity                                              (D)  very low 

 

             j.    The CE configuration is preferred in amplifiers than CB because of ________.

 

                   (A)  lower amplification factor             

                   (B)  larger amplification factor 

(C)  high input resistance and low output resistance           

(D)  None of these 

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

                                

  Q.2     a.   Describe the Construction and circuit operation of a DEMOSFET.                     (8)                                                                                                                                                                                                                                                               (10)

       

             b.   A voltage divider biasing circuit is shown in Fig.1 .Determine emitter current, collector–emitter voltage and collector voltage.

                  

 
                                                                                                                                            (8)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                              

 

 

 

 

  Q.3     a.   What is class A amplifier? Draw and explain the Darlington transistor

                    configuration in brief.                                                                                         (8)                                                               Transistor   Configurations in brief                                                                         (8)

 

             b.   Explain the concept of Harmonic distortion in power amplifier.                            (8)

       

  Q.4           a.                                                        Describe the construction and working principle of Quartz crystal. Explain the role of Quartz crystal in crystal oscillator in detail.                              (8)

 

             b.   A Colpitts Oscillator circuit having two capacitors of 10 pF and 100 pF respectively are connected in parallel with an inductor of 10 mH. Determine the frequency of oscillations of the circuit. Draw the circuit diagram using these components.                                                                                             (8)

                  

  Q.5     a.   Draw and describe the circuit operation of Astable 555 Multivibrator.                 (8)

                  

             b.   Explain the circuit as shown in Fig.2 and draw the output of the circuit.                (8)

              
 
 

 

 

 

 

 

 

 


                Q.6    a.   How square wave is generated from op-amp based square wave generator? Draw and explain the circuit

       .                                                                                                                                    (8)

             b.  Design a bandpass active filter with a single op-amp to meet the following                    specifications.    

                   f1 = 3 kHz             fh = 3.5 kHz        Ao = –5                                                            (8)

 

  Q.7     a.   Explain the working principle of Integrator. List the applications of integrator.                      (8)   

 

             b.   How does the transistor work as switch?  Explain the output characteristics of a transistor.                                  (8)  

 

  Q.8    a.                                                              What is the Common Nomenclature of n- channel FET amplifier? Explain         each region in brief.                                                                        (8)

 

 b.   In a CE amplifier circuit, the following quantities are measured

 (i) When ac output is short circuited (i.e. VCE=0)

                    Ib = 15 µA   IC = 1.5 mA  Vbe= 15 mV

 

(ii)      When ac output is open circuited  ( Ib=0)

   Vbe= 1 mV, Ic = 90 µA VCE= 1.5 V                     

Determine all the h-parameters of the circuit. Assuming that all the values are ac rms.

                                                                                                                                    (8)

                  

                                                                                                                                                

               Q.9   a.   Write Short note on the following:

                     (i)   Tuned Amplifier.        

                     (ii)  Source follower.                                                                                        (8)

 

             b.   The gain of an amplifier without feedback is 100 whereas with negative                          feedback it falls to 50. If due to ageing the amplifier gain falls to 80, find the                         percentage reduction in stage gain.

                   (i)  Without feedback.

                   (ii) With negative feedback.                                                                                (8)