250+ TOP MCQs on Introduction to Oscillator and Answers

Analog Circuits Multiple Choice Questions on “Introduction to Oscillator”.

1. Oscillators are used to ______ AC voltage.
A. Prevent
B. Generate
C. Amplify
D. Rectify
Answer: B
Clarification: Oscillators are used for generating AC voltage. They are often characterized by the frequency of the oscillations produced. There are two main types of electronic oscillators, linear/harmonic and nonlinear/relaxation oscillator.

2. Oscillator __________ an AC input for giving an AC output.
A. Doesn’t need
B. Need
C. Doesn’t need at lower frequencies
D. Doesn’t need at higher frequencies
Answer: a
Clarification: An oscillator is an amplifier with positive feedback. It usually has a noise which is an amplifier as an oscillating output. They do not require any type of specific input to function properly.

3. Negative resistance are incorporated in oscillator for ___________
A. Sustained oscillation
B. Damped oscillation
C. Biasing the oscillator
D. Increasing amplitude of oscillation
Answer: A
Clarification: Negative resistance are incorporated in oscillator for sustained oscillation. Negative resistance will cancel the damping by positive (normal) resistance.

4. For accomplishing negative resistance in oscillator we use _____________
A. Voltage divider circuit
B. Negative feedback
C. Positive feedback
D. Current divider circuit
Answer: C
Clarification: The input or output impedance of an amplifier with positive feedback applied, can be negative. When loop gain is greater than 1, the input impedance is a negative value, over a linear range. These are also called active resistors.

5. Primary trigger for oscillation is obtained from ___________
A. DC voltage
B. Noise voltage
C. External trigger voltage
D. No trigger is required
Answer: B
Clarification: The primary trigger for oscillation is obtained from noise voltage.

6. The AC power of output signal is obtained by ___________
A. Input AC voltage
B. Input DC voltage
C. DC biasing voltage
D. Power is generated by transistor itself
Answer: C
Clarification: The Ac power of output signal is obtained by DC biasing voltage of amplifier.

7. The output of a stable oscillator have ___________
A. Constant amplitude
B. Varying amplitude
C. Constant amplitude at high frequencies only
D. Constant amplitude at low frequencies only
Answer: a
Clarification: Output of a stable oscillator have constant amplitude and frequency. A common criteria is the Barkhausen stability criteria, wherein it states that loop gain should be unity and feedback should be positive.

8. The output waveform of a stable oscillator have ___________
A. Constant frequency at low amplitude only
B. Constant frequency at high amplitude only
C. Variable frequency
D. Constant frequency
Answer: D
Clarification: Output of a stable oscillator have constant amplitude and frequency.

9. In an oscillator if phase of feedback is same as that of oscillation waveform then feedback is called ___________
A. Positive feedback
B. Negative feedback
C. Cannot be predicted
D. Either positive or negative depending upon frequency
Answer: A
Clarification: In an oscillator if phase of feedback is same as that of oscillation waveform then feedback is called positive feedback.

10. The output of oscillator will not depend upon ___________
A. Feedback
B. Amplifier
C. Both feedback and amplifier
D. Input voltage
Answer: D
Clarification: The output of the oscillator will not depend upon input voltage. There is no input voltage for an oscillator.

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