ECE 421 Oscillators Quiz

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?

5 Hz - 1 MHz (D) Signup and view all the answers

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

-180 degrees (A) Signup and view all the answers

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

Open circuit at C2 and short circuit at C1 (B) Signup and view all the answers

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

To counter the attenuation of the lead lag network (D) Signup and view all the answers

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

180O (D) Signup and view all the answers

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

Contributes an extra 180O phase shift (C) Signup and view all the answers

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

Stabilize oscillation frequency (C) Signup and view all the answers

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

Band-stop response (B) Signup and view all the answers

What components are used for frequency determination in LC Oscillators?

LC Tank circuits (B) Signup and view all the answers

What is the condition for N parallel resonance to occur?

Inductive reactance equals parallel capacitance reactance (C) Signup and view all the answers

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

1kHz (B) Signup and view all the answers

What type of waveform does a relaxation oscillator typically generate?

Square wave (B) Signup and view all the answers

What is a common device used in a relaxation oscillator?

Schmitt trigger (D) Signup and view all the answers

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

4.5V to 18V (A) Signup and view all the answers

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

$\frac{tH}{tH + tL} \times 100%$ (B) Signup and view all the answers

What is the primary function of an oscillator?

To generate repetitive waveforms (D) Signup and view all the answers

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

Self-sustaining oscillator (A) Signup and view all the answers

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

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 (A) Signup and view all the answers

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

A feedback oscillator uses a feedback loop, while a relaxation oscillator does not (C) Signup and view all the answers

What is the output of an oscillator?

A repetitive waveform (C) Signup and view all the answers

What is the purpose of using oscillators in electronics?

To generate high frequency carriers, clocks, and timing circuits (D) Signup and view all the answers

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

To provide a stable, precise frequency (A) Signup and view all the answers

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

Crystal Oscillator (D) Signup and view all the answers

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

Elasticity (C) 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?