Code: DC-02                                                  Subject: FUNDAMENTALS OF ELECTRONICS

Time: 3 Hours                                                                 June 2006                                    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 best alternative in the following:                                         (2x10)

a. The value of resistor having Red-Red-Red-Gold colour band is

(A) (B)

(C) (D) 

b. Which of the following will serve as a Donor Impurity in Silicon

(A) Boron                                          (B)  Indium

(C)  Germanium                                   (D)  Antimony

             c.   A PIN Diode is frequently employed as a

(A) Peak Clipper                               

(B) Voltage Regulator

(C) Switching Diode for frequencies up to GHZ range

(D) Harmonic generator

             d.   Transistor is a

(A) Current Controlled Current Device    

(B) Current Controlled Voltage Device    

(C) Voltage Controlled Current Device

(D)  Voltage Controlled Voltage Device   

             e.   In a JFET, when V_DS is increased beyond the Pinch-off voltage the Drain current

(A) increases                                      (B)  decreases

(C)  remains constant                           (D)  first decreases and then increases

             f.    One of the most widely used LC oscillators is

(A) the phase-shift oscillator.              (B)  the Hartley oscillator.

(C)  the Colpitts oscillator.                   (D)  the Clap oscillator.

             g.   A NOR gate is ON only when all the inputs are

(A) OFF                                            (B)  ON

(C)  Positive                                        (D)  Negative

             h.   Main advantage of ECL family of logic gates is its

(A) Low power dissipation                 (B) Low speed

(C)  Very large Fan-in                         (D) Extremely Low Propagation Time

             i.    According to Boolean Laws A+(BC) is equal to

(A) AB+C                                          (B) AB+AC

(C) A                                                  (D) (A+B) (A+C)

             j.    Op-amps have become very popular because

(A) They are very cheap                    

(B) They are extremely small in size

(C)  Their external characteristics can be altered to suit any application.

(D)  They are available in different packages.

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   What is an electrolytic capacitor? Why is it necessary to connect an electrolytic Capacitor in a circuit with correct polarity?                                  (3)

             b.   Define Voltage and Current Sources. Draw their equivalent circuit diagram.                        (3)

             c.   For a network shown in figure below calculate the load current for              R_L= 6 K by using Thevenin’s theorem.                                              (10)

Q.3     a.   What is an intrinsic semiconductor? Explain why the conductivity of a pure semiconductor increases with temperature.                                        (8)

             b.  What is an ideal diode? Draw and explain the V-I characteristics of an ideal diode?            (8)

Q.4     a.   How does a tunnel diode differs from a conventional P-N junction diode? With the help of its energy band diagram, explain its principle of operation in forward and reverse bias conditions. (10)

b.   Explain the characteristics of zener diode. Give its applications.                           (6)

Q.5     a.   Sketch a family of CE Output Characteristics for a BJT. Indicate the Active, Cut-off and saturation regions. Explain the shapes of the curves qualitatively.                                                                     (8)

     b.   In CE configuration shown in below fig, the collector supply voltage      V_cc = 10V, load resistance R_c is 8 K. Draw dc load line. Determine the operating point Q for zero signal if base current is 15  and  is 40.                                                      (8)

  Q.6     a. Distinguish between Enhancement type and Depletion type MOSFETs. Draw the structure of a N-channel Enhancement MOSFET and explain its operation with the help of neat diagram.  (8)

b.   What is meant by Negative feedback? Explain the advantages of Negative

       Feedback in amplifiers.                                                                                    (8)

Q.7      a.  State and explain De-Morgan’s theorems.                                              (6)

             b.  Realize NOT Gate, OR Gate and AND Gate using NOR Gates only.                 (4)

c. Prove the following expressions using Boolean Algebric Theorems.

                        (i)

                        (ii) (6)

Q.8   a.    What is a Karnaugh map and what for it is used? What is the difference between 

this map for minterms and maxterms?                                                                 (6)

           b.   Minimize the following four-variable logic function using Karnaugh map?

(6)

           c.   What are the different digital logic families? Compare any two of them.                (4)

Q.9     a. What are the ideal characteristics of an op-amp?                                               (5)

b.  Draw an op-amp differentiator circuit. Sketch its output waveform for a    

     sinewave input.                                                                                (6)

c.  What is an integrated circuit? Explain how a capacitor can be constructed in a    

     Monolithic Integrated Circuit.                                                                          (5)