Question

Among the following, identify the incorrect statement.
1. An oscillator is a circuit that convers DC to AC.
2. All oscillators generate sine wave.
3. An oscillator is an amplifier that supplies its own input signal.
4. In-phase feedback is called positive feedback.

Answer 1

Correct Answer - Option 2 : All oscillators generate sine wave.

Phase shift oscillator:

• The phase shift oscillator is a linear electronic circuit that produces a sine wave output.
• It consists of an inverting amplifier element such as a transistor or op-amp with its output feedback to its input through a phase shift network consisting of resistors and capacitors in a ladder network.
• The feedback network shifts the phase of the amplifier output by 1800 at the oscillation frequency to give positive feedback. 

 

Wein bridge oscillator :

• The Wein bridge oscillator uses two RC networks connected together to produce a sinusoidal oscillator.
• The Wein bridge oscillator uses a feedback circuit consisting of a series RC circuit connected with a parallel RC of the same component values producing a phase delay or phase advance depending upon the circuit frequency
• At the resonant frequency, the phase shift is 00.

 

Clapp oscillator:

• The Clapp oscillator is an LC oscillator that uses a particular combination of an inductor and three capacitors to set the oscillator frequency.
• The Clapp is often drawn as a Colpitts oscillator that has an additional capacitor placed in series with the inductor.
• This comes under linear or harmonic oscillators, which produces a sine wave output.
• Clapp oscillator is also one kind of phase shift oscillator containing L, C elements, and a transistor or op-amp along with feedback, so it provides phase shift.

 

​Relaxation oscillator:

• A relaxation oscillator is a nonlinear electronic oscillator circuit that produces nonsinusoidal repetitive output signals such as a triangle wave or square wave.
• Relaxation oscillators are generally used to produce low-frequency signals.
• These oscillators will not provide any phase shift in their output
• Examples of Relaxation oscillators are Astable multivibrator, flyback or sweep oscillator, etc.