JNTU
JNTU B.Tech III LINEAR AND DIGITAL IC APPLICATIONS Previous Question Paper (February - 2022 - R16)
Answer any five questions. All questions carry equal marks.
Main
Explain in detail all the DC and AC characteristics of an ideal OP-AMP with relevant expressions.
Answer
An ideal operational amplifier (Op-Amp) is a theoretical device with infinite performance parameters. Its DC and AC characteristics are defined as follows:
DC Characteristics:
- Infinite Open-Loop Gain (AOL = ∞): The voltage gain without feedback is infinite, meaning any differential input voltage results in an infinite output voltage.
- Infinite Input Impedance (Zin = ∞): No current flows into the input terminals, preventing loading of the source.
- Zero Output Impedance (Zout = 0): The Op-Amp acts as an ideal voltage source, maintaining a constant output voltage regardless of the load current.
- Zero Offset Voltage (Vos = 0): When both inputs are grounded, the output voltage is exactly zero.
- Infinite Common-Mode Rejection Ratio (CMRR = ∞): The device perfectly rejects signals common to both inputs, resulting in zero common-mode gain (Acm = 0).
AC Characteristics:
- Infinite Bandwidth (BW = ∞): The gain remains constant at all frequencies from DC to infinity.
- Infinite Slew Rate (SR = ∞): The output voltage can change instantaneously in response to an input step, meaning there is no distortion for high-frequency signals.
With a neat diagram explain the operation of instrumentation amplifier using Op-Amp and derive the necessary expression.
Answer
An instrumentation amplifier is a precision differential voltage-gain device designed for high input impedance and high CMRR. It typically consists of three Op-Amps: two as non-inverting buffers and one as a differential amplifier.
Operation: The first stage (two Op-Amps) provides high input impedance and differential gain, while the second stage (differential amplifier) rejects common-mode signals. By adjusting a single gain-setting resistor (Rg), the overall gain can be precisely controlled.
Derivation: Let the inputs be V1 and V2. The first stage output voltages are Vo1 and Vo2. The output of the differential stage is given by:
For the input stage, the differential gain is determined by the resistor Rg connected between the inverting terminals of the first two Op-Amps. The expression for the total gain is:
This configuration allows for high gain and excellent common-mode rejection, making it ideal for amplifying low-level signals from sensors.
Draw the circuit diagram of Differentiator using op-amp and explain its operation with relevant wave forms.
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With neat circuit diagram explain the working principle of IC 723 voltage regulator.
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Explain the operation of triangular-wave generator with a neat circuit and derive expressions for frequency of oscillations?
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Design an active low pass filter with a cut off frequency of 1 kHz and with a pass band gain of 2.
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Explain the astable operation of IC 555 with necessary waveforms.
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What is PLL? Explain its application as frequency multiplier.
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With a neat diagram explain the operation of Dual slope ADC.
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Discuss the limitations of R-2R Ladder DAC along with its principle of operation.
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State and explain the important specifications of DAC.
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Design a parallel binary adder circuit using 2’s complement system.
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Design a driving circuit for LED and state which 74XX series IC is used for it.
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Give the design considerations of parity encoder and explain the operation with relevant circuit.
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With a neat diagram, explain the architecture of RAM.
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Design a Mod-10 counter using JK flip-flops.
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