### Linear Integrated Circuits (LIC)–Question Bank 2012 Edition

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

QUESTION BANK

147404 - LINEAR INTEGRATED CIRCUITS

UNIT-I

IC FABRICATION AND CIRCUIT CONFIGURATION FOR LINEAR ICS

PART-A (2 MARKS)

1. Mention the advantages of integrated circuits.

2. Write down the various processes used to fabricate IC’s using silicon planar technology.

3. What is the purpose of oxidation?

4. Why aluminum is preferred for metallization?

5. What are the popular IC packages available?

6. Define an operational amplifier.

7. List out the ideal characteristics, and draw the equivalent diagram of an OP-AMP

8. Define Virtual ground property of an OP-AMP

9. Draw the voltage follower circuit of an OP-AMP

10. Define the following parameters as applied to an op-amp.

11. Why open loop op-amp configurations is not used in linear applications?

12. Determine the slew rate of the op-amp.

13. What is active load? Where it is used and why?

14. What is an Integrated circuit?

15. Mention the advantages of integrated circuits.

16. Write down the various processes used to fabricate IC’s using silicon planar technology.

17. What is the purpose of oxidation?

18. Why aluminum is preferred for metallization?

19. What are the popular IC packages available?

20. Define an operational amplifier.

21. List out the ideal characteristics, and draw the equivalent diagram of an OP-AMP

22. Define Virtual ground property of an OP-AMP

23. Draw the voltage follower circuit of an OP-AMP

24. Define the following parameters as applied to an op-amp:

i) Input bias current ii) Input offset current iii) Input offset current iv) C.M.R.R v) P.S.R.R vi) slew rate

25. Why open loop op-amp configurations is not used in linear applications?

26. In response to a square wave input, the output of an op-amp changed from -3V to

+3V over a time interval of 0.25µ s.

27. Determine the slew rate of the op-amp.

28. What is active load? Where it is used and why?

29. What is current mirror?

30. Determine the value of the resistance required for the Widlar current mirror shown in the figure, if the reference current is 1 mA and the control current (I ) is 10µ A.

31. In a constant current source with zener, the zener voltage is 6.2 V. Calculate the current I in the circuit shown in the figure.

PART-B

1. Explain in detail the fabrication of ICs using silicon planar technology.(16)

2. (i) Explain the process of epitaxial growth IC fabrication with neat diagram. (8) (ii) Explain the importance of isolation and discuss the method of isolation. (8)

3. (i) Explain the process of photolithography.(8)

(ii) Explain the process of Al metallization.(8)

4. (i) With neat circuit circuit diagram and with necessary eqations, explain the concept of Wildar current source used in op- amp circuit. (16)

5. Explain the operation of differential amplifier and give its differential gain, common mode gain and CMRR. (16)

6. (i) Explain the method of improving the slew rate of an op-amp.(12)

(ii) Draw and explain briefly the equivalent circuit of an op-amp. (4)

7. Draw and explain the internal block diagram of an op-amp.(16)

8. (i) Discuss dominat pole frequency compensation in operational amplifier. (8)

(ii) Define slew rate. Explain the cause of slew rate and derive an expression for slew rate for voltage follower.(8).

9. (i) What is an active load? Explain the CE amplifier with active load.(8)

(ii) Explain pole-zero compensation. (8)

10. Explain the AC and DC characteristics of an op-amp.

UNIT-II

APPLICATIONS OF OPERATIONAL AMPLIFIERS

PART-A ( 2 MARKS)

1. Give some applications of Comparator.

2. What is a window detector?

3. List the types of comparators.

4. Differentiate Schmitt trigger and comparator.

5. What are the limitations of an ideal active differentiator?

6. State the important features of an instrumentation amplifier.

7. How does the precision rectifier differ from the conventional rectifier?

8. What are the advantages of active filters over the passive filters?

9. Draw the freq. response of the LPF.

10. What is an antilog amplifier? Draw the circuit of an antilog amplifier.

11. What is a V to C convertor?

12. Draw the circuit of an integrator.

13. Why integrators are preferred over differentiators in analog computers?

14. Give some applications of Comparator.

15. What is a window detector?

16. List the types of comparators.

17. Differentiate Schmitt trigger and comparator.

18. What are the limitations of an ideal active differentiator?

19. State the important features of an instrumentation amplifier.

20. How does the precision rectifier differ from the conventional rectifier?

21. What are the advantages of active filters over the passive filters?

22. Draw the freq. response of the LPF.

23. What is an antilog amplifier? Draw the circuit of an antilog amplifier.

24. What is a V to C convertor?

25. Draw the circuit of an integrator and give its output waveform.

26. Two voltages +V1 and +V2 are available. Using two operational amplifiers draw a circuit to compute 5V1-3V2.

27. Why integrators are preferred over differentiators in analog computers?

PART-B

1. Show with help of circuit diagram an op-amp used as

(i) Scale changer,

(ii) Phase shifter,

(iii) Inverting adder and Non- inverting adder. Draw an op-amp circuit whose output is V1+V2-V3-V4.(16)

2. (i) Explain the operation of Schmitt trigger (10)

(ii) Explain log amplifier (6)

3. (i) Discuss the working of instrumentation amplifier. Name two applications of the same.(10)

(ii) An input dc voltage shown in figure is fed to an op-amp integrator with RC = 1 sec. Find the output and sketch. Op- amp is nulled initially. (6)

4. (i) Design an op – amp Schmitt trigger with VUT= 2V, VLT= -4V & the output swings b/w +10V. If the i/p is 5 sin wt , plot i/p & o/p waveforms.(8)

(ii) Design a circuit to implement Vo=0.545V3+0.273V4-1.25V1-2V2. (8)

5. (i) Draw the circuit diagram of a second order butter worth active low pass filter and derive an expression for its transfer function.(10)

(ii) Design the above mentioned filter for a cutoff frequency of 1 KHz and a damping factor of 1.4.(6)

6. (i) Design a second order Butterworth active high pass filter for a cutoff frequency of 5 kHz. (10)

(ii) Explain antilog amplifier (6)

7. (i) Design an op-amp circuit to give an output voltage V0=3V1-2V2+5V3 where V1, V2, and V3 are inputs.(8)

(ii) What is a precision diode? With circuit schematic explain the working principle of full wave precision rectifier. (8)

8. (i) Explain a positive clipper circuit usig an op-amp and a diode with neat diagrams.(8)

(ii) Explain a simple op-amp differentiator. Mention its limitations. Design an op-amp differentiator that will differentiate an input signal with fmax=100Hz.

UNIT III

ANALOG MULTIPLIER AND PLL

PART-A (2 MARKS)

1. List out the blocks of PLL.

2. Define the following terms related to PLL, a) Capture range

b) Lock range.

3. Draw the types of low pass filter circuits involved in PLL.

4. Write the expression of a) capture range

b) lock range

5. Define voltage to frequency conversion factor of VCO.

6. Mention the applications of analog multipliers.

7. List out the applications of PLL.

8. Define phase transfer conversion coefficient of PLL.

9. Briefly write on frequency synthesizers.

10. Explain how a frequency doubler can be realized using analog multiplier.

11. What is a compander IC?

12. What is a peak detector?

13. Draw the functional block diagram of a PLL circuit.

14. What are the advantages emitter coupled pair?

PART-B

1. (i) With circuit diagram, explain the working of variable transconductance multiplier. What is its limitation? (10)

(ii) How an analog multiplier used as frequency doubler? (6)

2. Explain the working of four quadrant Gilbert cell multiplier circuit.(16)

3. What are the building block of PLL explain its working.(16)

4. (i) Draw and explain the operation of VCO IC 566 and derive the expression for fo.(10)

5. (ii) Explain the frequency synthesizer using PLL. (8)

6. Explian the monolithic PLL NE/SE 565 with necessary diagrams.(16)

7. (i) Derive the expression for capture range and lock- in-range of PLL.(10) (ii) What are the functions of LPF in PLL?(6)

8. Explain the applications of PLL.(16)

9. Explain various types of phase detectors used in PLL.(16)

UNIT-IV

ANALOG TO DIGITAL AND DIGITAL TO ANALOG CONVERTERS

PART-A (2 MARKS)

1. Explain the operation of basic sample and hold circuit.

2. State the advantages and applications of sample and hold circuits.

3. List the drawbacks of binary weighted resistor technique of D/A conversion.

5. The basic step of a 9 bit DAC is 10.3 mV. If 000000000 represents 0Volts, what is the output an input of 101101111?

6. Why does the dual slope ADC provide excellent noise rejection of AC signal whose periods are integral multiples of the integration time?

7. Find the resolution of a 12 bit DAC converter.

8. Draw the monolithic sample and hold IC.

10. Define start of conversion and end of conversion.

11. What are the types of ADC and DAC.

12. What is the difference between direct ADC and integrating type ADC.

13. Which is fastest ADC? State the reason.

PART-B

1. Explain the operation of R-2R ladder type DAC and the weighted resistor type DAC(16)

2. (i) Draw and explain the operation of sample and hold circuits. (8) (ii) Explain the operation of inverted R-2R ladder type DAC. (8)

3. (i) Draw and explain the functional diagram of the successive approximation ADC converter. (8) (ii) Explain the working of Flash ADC.(8)

4. (i) A dual slope ADC uses a 16 bit counter and a 4 MHz clock rate. The maximum input voltage is =10V. The maximum n integrator output voltage should be -8V when the counter has cycled through 2 counts. The capacitor used in the integrator is 0.1µ F. Find the value of the resistor R of the integrator. If the analog signal is = 4. 129 V, find the corresponding binary number. (8)

(ii) How many bits are required to design a DAC that can have a resolution of 5mV? The ladder has =8V full scale. (8)

5. Explain the principle of operations.

6. (i) Define following performance parameters of D/A converters: (8)

a) Resolution

b) Accuracy

c) Monotonicity

d) Conversion time

(ii) Explain the following with reference of ADC: (8)

a) Conversion time b) Accuracy

c) Resolution time

d) Quantization time

7. (i) How many comparators are required for a 4-bit flash ADC? For an input signal in the range of 0 to +10V. What are the reference voltages needed? Show how they can be generated using a 10V reference and several 1 Kohm resistors.(8)

(ii) Explain the over sampling A/D convertor with functional block diagram.(8)

8. (i) Explain the voltage to time convertor with functional block diagram.(8) (ii) Explain the switches for DAC.(8)

UNIT-V

SPECIAL FUNCTION INTEGRATED CIRCUITS

PART-A (2 MARKS)

1. What are the operating modes of a 555 timer?

2. List out the applications of 555 timer?

3. Define sink current and source current?

5. What is the use of reset pin of 555 timer?

6. What is the purpose of control voltage pin (5) of 555 timer?

7. List out the major blocks of 555 timer functional diagram?

8. Define duty cycle?

9. Write the expression for pulse width of 555 timer in monostable mode?

10. Write the expression for total time period of 555 timer in astable mode?

11. What is the frequency of oscillation of free running mode of 555 timer?

12. List out the applications of 555 timer in astable mode

13. List out the applications of 555 timer in monostable mode

14. Define voltage regulators and give the types?

15. What do you mean by linear voltage regulators?

16. Define switched voltage regulators?

17. What are the advantages of adjustable voltage regulators over the fixed voltage regulators?

19. List out the parameters related to the fixed voltage regulators?

20. Define dropout voltage of a fixed voltage regulator?

21. What is an opto-coupler IC? Give examples.

22. Mention the advantages of opto-couplers.

23. What is an isolation amplifier?

24. Draw the internal circuit for audio power amplifier.

PART-B

1. (i) Explian the operation of Triangular wave generator.(8) (ii) Explian the operation of Sine wave generator. (8)

2. Explain the various types multivibrators using op-amp.(16)

3. (i) With diagram explain the working principle of ICL 8038 function generator. (10)

(ii) Explain the operation of Saw tooth wave generator op-amp.(16)

4. Explain in detail the function of 555 timer in astable mode and derive the expression for frequency of oscillation.(16)

5. Explain in detail the function of 555 timer in monostable and derive the expression for frequency of oscillation.(16)

6. (i) Draw the internal functional diagram of 555 timer and explain briefly about each pin . (10)

(ii) Write a short note on Optocouplers?(6)

7. (i) How is voltage regulators classified? Explain a series voltage regulator.(8)

(ii) Explain the operation of frequency to voltage convertors.(8)

8. Explain the operation of IC723 and design an adjustable voltage regulator using IC 723 to obtain positive low voltage and high voltage.(16)

(i) Power amplifiers (5)

(ii) Tuned amplifiers (5)

(iii) Video amplifiers (6)

10. (i) Explain LM 380 Audio amplifier(10)

(ii) Discuss about protection circuit used in IC regulators.(6)

11. (i) Explain the F/V convertor with a neat diagram.(10)

(ii) Draw the circuit of a switched capacitor filter and explain. (6)

12. (i) With diagram explain the working principle of ICL 8038 function generator. (10) (ii) What are the different sources of error in D/A convertor. (6)