Analog Circuits Questions and Answers – Introduction to Oscillator

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This set of Analog Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Introduction to Oscillator”.

1. Oscillators are used to ______ AC voltage.
a) Prevent
b) Generate
c) Amplify
d) Rectify
View Answer

Answer: b
Explanation: 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.
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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
View Answer

Answer: a
Explanation: An oscillator is an amplifier with positive feedback. It usually has a noise which is 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
View Answer

Answer: a
Explanation: 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
View Answer

Answer: c
Explanation: 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
View Answer

Answer: b
Explanation: The primary trigger for oscillation is obtained from noise voltage.
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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
View Answer

Answer: c
Explanation: 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
View Answer

Answer: a
Explanation: 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
View Answer

Answer: d
Explanation: 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
View Answer

Answer: a
Explanation: In an oscillator if phase of feedback is same as that of oscillation waveform then feedback is called positive feedback.
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10. The output of oscillator will not depend upon ___________
a) Feedback
b) Amplifier
c) Both feedback and amplifier
d) Input voltage
View Answer

Answer: d
Explanation: The output of oscillator will not depend upon input voltage. There is no input voltage for an oscillator.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn