Q.1
The twin-T oscillator produces a ________ response.
  • low-pass
  • high-pass
  • band-pass
  • band-stop
Q.2
For frequencies up to 1 MHz, the ________ is the most widely used type of sinusoidal RC oscillator.
  • Wien-bridge
  • phase-shift
  • twin-T
  • None of these
Q.3
The start-up gain of an oscillator must be ________ one.
  • equal to
  • less than
  • greater than
  • All of above
Q.4
In the IC phase-shift oscillator, what should the ratio of feedback resistor Rf to R1 be?
  • Zero
  • Greater than –29
  • Less than 29
  • Any value
Q.5
At series resonance, the impedance of a crystal is
  • minimum.
  • maximum.
  • equal.
  • zero.
Q.6
The lead-lag circuit in the Wien-bridge oscillator has a resonant frequency at which the attenuation is
  • 1/2.
  • 1/4.
  • 1/3.
  • 1/5.
Q.7
An input signal is needed for an oscillator to start.
  • True
  • False
Q.8
What is the total phase shift requirement, around the feedback loop, for a phase-shift oscillator?
  • 90°
  • 180°
  • 270°
  • 360°
Q.9
The Nyquist plot combines the two Bode plots of gain versus frequency and phase shift versus frequency on a single plot.
  • True
  • False
Q.10
One condition for positive feedback is that the phase shift around the feedback loop must be ________°.
  • 0
  • 90
  • 180
  • 45
Q.11
The amplifier is unstable if the Nyquist curve plotted encloses (encircles) the –1 point, and it is stable otherwise.
  • True
  • False
Q.12
Which of the following oscillators is (are) tuned oscillators?
  • Colpitts
  • Hartley
  • Crystal
  • All of the above
Q.13
What is the ratio of the output impedance with series feedback to that without feedback?
  • 1
  • 1 + A
  • A
  • A
Q.14
What is the ratio of the input impedance with series feedback to that without feedback?
  • 1 + A
  • A
  • 1
  • All of above
Q.15
In order to start up, a feedback oscillator requires
  • negative feedback less than 1.
  • positive feedback greater than 1.
  • unity feedback equal to 1.
  • no feedback.
Q.16
Which of the following is required for oscillation?
  • A > 1
  • The phase shift around the feedback network must be 180º.
  • Both A > 1 and the phase shift around the feedback network must be 180º.
  • None of the above
Q.17
A circuit that can change the frequency of oscillation with an application of a dc voltage is sometimes called
  • a voltage-controlled oscillator.
  • a crystal oscillator.
  • a Hartley oscillator.
  • an astable multivibrator.
Q.18
The feedback signal in a(n) ________ oscillator is derived from a capacitive voltage divider in the LC circuit.
  • Hartley
  • Armstrong
  • Colpitts
  • None of these
Q.19
Sinusoidal oscillators operate with ________ feedback.
  • positive
  • negative
Q.20
For a phase-shift oscillator, the gain of the amplifier stage must be greater than ________.
  • 19
  • 29
  • 30
  • 1
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