JNTU
JNTU B.Tech III LINEAR AND DIGITAL IC APPLICATIONS Previous Question Paper (January/February - 2021 - R16)
Answer any five questions. All questions carry equal marks.
Main
Derive the expression for the output voltage of a non inverting amplifier.
Answer
In a non-inverting amplifier, the input signal is applied directly to the non-inverting terminal (+) of the operational amplifier, while a portion of the output is fed back to the inverting terminal (-) through a voltage divider network consisting of resistors Rf and R1.
Assuming an ideal op-amp, the voltage at the inverting terminal (V-) is equal to the voltage at the non-inverting terminal (V+) due to the virtual short concept. Thus, V- = Vin.
The voltage at the inverting terminal is determined by the voltage divider rule applied to the output voltage (Vout):
Equating V- to Vin:
Rearranging for the output voltage:
The term (1 + Rf/R1) represents the closed-loop gain of the non-inverting amplifier.
Draw the circuit diagram of a Schmitt trigger and explain its functioning.
Answer
A Schmitt trigger is a comparator circuit with positive feedback that introduces hysteresis to prevent noise from causing multiple output transitions. It consists of an op-amp with the input signal applied to the inverting terminal (-) and a feedback network connected to the non-inverting terminal (+).
The circuit uses two resistors, R1 and R2, to create a voltage divider that sets the reference voltage at the non-inverting terminal based on the output state. The two threshold levels, Upper Threshold Voltage (VUT) and Lower Threshold Voltage (VLT), are defined as:
When the input voltage Vin is less than VLT, the output is at +Vsat. As Vin increases and crosses VUT, the output switches to -Vsat. The output remains at -Vsat until Vin drops below VLT, at which point it switches back to +Vsat. This hysteresis loop ensures that the circuit is immune to small fluctuations or noise around the threshold points.
List the advantages of instrumentation amplifier. Derive the expression for gain of instrumentation amplifier.
Answer
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Design a Integrator to integrate an input signal that varies in frequency from 1 KHz to 10 KHz and plot the output wave forms if the input is a sine wave of 1V peak at 1 KHz.
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Design a first order low pass Butter width filter at a cut off frequency of 1 MHz with a passband gain of 2. Further using frequency scaling technique convert the 1 KHz cut off frequency of the low pass filter to a cut off frequency of 1.6 KHz.
Answer
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Design Triangular wave generator circuit using Op-Amp.
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Design a second order Active Band pass filter to transmit frequencies in the range of 2 KHz to 12 KHz, given 2K=1.414. Assume necessary data.
Answer
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Using the 555 timer, design a monostable multivibrator having an output pulse width of 100 ms.
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Give the schematic circuit of integrating type A/D converter and explain the operation of this system and derive expression for output voltage Vo.
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Which type of DAC is more preferable? Draw the circuit diagram and obtain expression for output voltage for 4 bits.
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Give the schematic circuit of successive approximations A/D converter and explain its operations.
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Explain how the deficiencies of weighted resister type DAC can be overcome through an R-2R ladder type network. Explain the conversion procedure in R-2R ladder type DAC.
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Explain sinking current and sourcing current of TTL output. Which of the parameters decide the fan-out and how?
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Draw the functional truth table and schematic of 4 – bit parallel binary adder.
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Explain the working of clocked RS and clocked D flip-flop.
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Design a 3 – bit binary synchronous counter.
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