JNTU previous papers B Tech 1st Sem Examinations,Linear and digital IC application, November 2008

JNTU previous papers

JNTU, B.Tech,I-Semester


( Computer Science & Engineering, Information Technology and Computer Science & Systems Engineering)



1. (a) Why is emitter resistor RE replaced by a constant current bias circuit in differential amplifier stage of an OP-AMP? [3]

(b) Explain why open loop configurations are not used in linear applications [4]

(c) For an OP-AMP, PSRR=70dB(min),CMRR=105,differential mode gainAd=105.

The output voltage changes by 20V in 4 microseconds. Calculate i)numerical

value of PSRR ii) Common mode gain iii) Slew rate of the OP-AMP. [9]


2. (a) What is a clipper? With circuit diagram, explain the operation of positive

and negative clippers [10]

(b) Describe the principle of operation of a precision half wave rectifier with wave forms [6]


3. (a) What feedback is preferred for oscillators and why? What is the effect of negative feedback? [8]

(b) Design an OP-AMP based relaxation oscillator and derive the frequency of

oscillation. [8]


4. (a) Explain the operation of Monostable multivibrator using 555 timer. Derive

the expression of time delay of a Monostable multivibrator using 555 timer.


(b) Design a Monostable multivibrator using 555 timer to produce a pulse width

of 100 m sec. [6]


5. Discuss the significance of phase detector, Low pass filter, amplifier and a VCO in

PLL. [16]


6. (a) Explain the operation of a delay equalizer circuit with neat sketches. Derive

an expression relating input and output voltages of the equalizer. [8+2]

(b) For the all pass filter, determine the phase shift between input and output at

f=2 kHz. To obtain a positive phase shift. What modifications are necessary

in the circuit? [6]


7. (a) What is meant by AOI Logic. Explain with the help of example. [6]

(b) Draw the circuit of an improved version of D.T.L. 3-input Nand gate, and explain its operations with the help of Truth Table If hFE of each transistor is 40, find FAN-OUT of the circuit. [10]


8. (a) List out different types of A/D converters and compare their merits and de-

merits. [8]

(b) Give the schematic circuit of an A/D converter widely used in digital volt-

meters and explain its operation. Derive expression for output voltage. [8]

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