JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III PULSE AND DIGITAL CIRCUITS Previous Question Paper (November/December - 2018 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
PART - A
Why the capacitor in an RC high-pass circuit is called a blocking capacitor?
Answer
The capacitor in an RC high-pass circuit is called a blocking capacitor because it acts as an open circuit to DC signals (zero frequency), effectively blocking any DC component from reaching the output while allowing AC components to pass.
How can the rate of rise of a pulse be measured by using a differentiator?
Answer
A differentiator produces an output voltage proportional to the rate of change of the input signal, defined by the formula:
By measuring the peak output voltage during the transition of a pulse, the slope or rate of rise (dv/dt) can be calculated if the RC time constant is known.
What do you mean by a regenerative comparator?
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What do you mean by biased clamping?
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What is pedestal? What are the effects of it in sampling gates?
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What is a sampling gate? What are the applications of it?
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Define cut off and saturation region.
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What are the drawbacks of a circuit which is used to eliminate a pedestal?
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What is the most widely used digital IC family?
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What is totem pole configuration and state the advantages?
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PART - B
Derive the expression for percentage tilt P of a square wave output of a RC high pass circuit.
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Why compensation is required in attenuator circuits? Derive the expression for perfect compensation.
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Derive the output equations and draw the output waveforms of a RC high pass circuit for the square wave and ramp signals as inputs.
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What is the amplitude and gain of a sinusoidal input in a RC high pass circuit?
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Explain the breakdown voltage consideration of transistor. Derive expression for BVCEO in terms of BVCBO.
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State and prove clamping circuit theorem.
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For a 2-level clipper with peak input 100V and forward bias diode reference voltage 75V and reverse bias diode reference voltage 50V, sketch the transfer characteristics, input and output voltage waveforms. Consider the diodes as ideal.
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Explain the operation of a transistor as switch with its switching characteristics.
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Define the following for transistor switch: (i) Rise time (ii) Fall time (iii) Storage time (iv) Delay time (v) Switch ON time (vi) Switch OFF time.
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Draw the circuits for the two types of the 4 diode bidirectional sampling gates and explain their operation. Derive the expression for Gain, Vc min and Vn min for these gates.
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Draw the circuit for the 6 diode bidirectional sampling gate and explain its operation.
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Draw the characteristics of the UJT. Draw the circuit diagram of the relaxation oscillator and obtain the value of the frequency of the same.
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Design a monostable multivibrator circuit that produces a pulse width of 10ms. Assume hfe= 30, VCE(sat)=0.3V, VBE(sat)= 0.7V, Ic(sat)=5mA, Vcc=6V, VBB= -1.5V.
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Explain the basic principle of working of Boot-strap time base generator. Draw the circuit diagram for the transistor based boot-strap time base generator and derive the expressions for Ts and Tr for the same.
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Design a 2 input NOR gate using RTL and DCTL logic family and explain its operation.
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With the help of a circuit diagram and waveforms, explain about astable multivibrator.
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Design a 2 input TTL NAND gate with totem-pole output and explain its operation.
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With the help of a circuit diagram and waveforms, explain how frequency division is done by a Mono-stable multivibrator?
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