ECE 421 Oscillators Quiz
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Questions and Answers

What is one of the requirements for a feedback oscillator?

  • Digital signal processing
  • Amplification (correct)
  • Negative feedback
  • Voltage regulation

    • In a feedback oscillator, what does positive feedback do?

  • Introduces phase shift
  • Reduces the frequency of oscillation
  • Damps the oscillations
  • Increases the amplitude of the output signal (correct)

    • What happens when the condition Acl > 1 during the start-up of an oscillator?

  • Output voltage amplitude builds up (correct)
  • Phase shift increases
  • Output voltage decreases
  • Oscillation stops abruptly

    • What frequency range is the Wien-Bridge Oscillator commonly used in?

    <p>5 Hz - 1 MHz</p> Signup and view all the answers

    At the frequency of oscillation, what is the total phase shift in a Wien-Bridge Oscillator?

    <p>-180 degrees</p> Signup and view all the answers

    What prevents extremely low and high frequencies from appearing at the output in a Wien-Bridge Oscillator?

    <p>Open circuit at C2 and short circuit at C1</p> Signup and view all the answers

    What is the purpose of the attenuation factor 3 in the Wien-bridge oscillator?

    <p>To counter the attenuation of the lead lag network</p> Signup and view all the answers

    In the Phase Shift Oscillator, what is the total phase shift required for oscillation at the frequency?

    <p>180O</p> Signup and view all the answers

    What role does the inversion of the op-amp play in the Phase Shift Oscillator?

    <p>Contributes an extra 180O phase shift</p> Signup and view all the answers

    What is the purpose of the feedback circuit attenuation factor in the Phase Shift Oscillator?

    <p>Stabilize oscillation frequency</p> Signup and view all the answers

    What type of response is produced by the parallel filters in the Twin-T Oscillator?

    <p>Band-stop response</p> Signup and view all the answers

    What components are used for frequency determination in LC Oscillators?

    <p>LC Tank circuits</p> Signup and view all the answers

    What is the condition for N parallel resonance to occur?

    <p>Inductive reactance equals parallel capacitance reactance</p> Signup and view all the answers

    At what frequency is the parallel resonant frequency usually higher compared to the series resonant frequency?

    <p>1kHz</p> Signup and view all the answers

    What type of waveform does a relaxation oscillator typically generate?

    <p>Square wave</p> Signup and view all the answers

    What is a common device used in a relaxation oscillator?

    <p>Schmitt trigger</p> Signup and view all the answers

    In the 555 IC Timer, what is the supply voltage range?

    <p>4.5V to 18V</p> Signup and view all the answers

    What is the formula for the duty cycle in the astable operation of a 555 IC Timer?

    <p>$\frac{tH}{tH + tL} \times 100%$</p> Signup and view all the answers

    What is the primary function of an oscillator?

    <p>To generate repetitive waveforms</p> Signup and view all the answers

    What type of oscillator does not require an external trigger signal?

    <p>Self-sustaining oscillator</p> Signup and view all the answers

    What is the condition for a feedback circuit to sustain oscillations?

    <p>The net voltage gain around the feedback loop must be unity or greater, and the net phase shift around the loop must be a positive integer multiple of 360O</p> Signup and view all the answers

    What is the difference between a feedback oscillator and a relaxation oscillator?

    <p>A feedback oscillator uses a feedback loop, while a relaxation oscillator does not</p> Signup and view all the answers

    What is the output of an oscillator?

    <p>A repetitive waveform</p> Signup and view all the answers

    What is the purpose of using oscillators in electronics?

    <p>To generate high frequency carriers, clocks, and timing circuits</p> Signup and view all the answers

    What is the primary function of a crystal in a crystal oscillator?

    <p>To provide a stable, precise frequency</p> Signup and view all the answers

    Which of the following oscillator circuits does not use an LC tank circuit?

    <p>Crystal Oscillator</p> Signup and view all the answers

    What is the mechanical property of crystal lattices that allows them to exhibit piezoelectric effect?

    <p>Elasticity</p> Signup and view all the answers

    Which of the following oscillators does not have a formula for its output frequency mentioned in the provided content?

    <p>Crystal Oscillator</p> Signup and view all the answers

    Which of the following is not a feedback oscillator circuit?

    <p>RC Oscillator</p> Signup and view all the answers

    What happens to the inductive reactance at series resonance in a crystal oscillator?

    <p>It is cancelled by the reactance of Cs</p> Signup and view all the answers

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