Difference between Amplifier and Oscillator

Differences Digital Electronics Electronics & Electrical

In electronics and communication engineering, amplifiers and oscillators are two important circuits. The major difference between an amplifier and an oscillator is that an amplifier increases the magnitude of a signal, while an oscillator generates an oscillating signal. However, there are many more differences between an amplifier and an oscillator that we shall learn in this article.

But, before highlighting the differences, let's get a brief overview of what amplifiers and oscillators are.

What is an Amplifier?

An amplifier is an electronic circuit which accepts a weak signal as its input and produces an output signal of high magnitude or intensity.

An amplifier uses a source of DC power to increase the energy or intensity of the weak signal. It because an amplifier does not generate energy on its own. A simple amplifier circuit can be designed by using a BJT (bipolar junction transistor). When a bipolar junction transistor is operated in active region, it functions as an amplifier and can amplify the weak signals.

In practice, a BJT in common emitter configuration is used as an amplifier. In the CE circuit of BJT, the weak signal is fed to the circuit through base-emitter terminals. As the base region is very small so the entire current will pass through the collector and the signal of increased magnitude is obtained at load terminals by connecting a load resistor.

Based on the number of transistors used, the amplifier may be a single stage amplifier or a multistage amplifier. When, the amplifier circuit contains only one transistor, then it is called a single stage amplifier. On the other hand, if there are multiple transistors used in the amplifier circuit, it is called a multistage amplifier.

Also, amplifiers can be classified depending on the type of parameter of the signal amplified, which are voltage amplifier, current amplifier and power amplifier.

What is an Oscillator?

An oscillator is an electronic circuit that has ability to generate electric signal having waveforms either sinusoidal or non-sinusoidal. Therefore, an oscillator acts like a source of alternating current (AC).

Oscillators are designed according to the requirement of frequency for a specific application, like an audio frequency oscillator circuit implemented such that it can produce signals of audio frequency.

The operation of a sinusoidal oscillator is quite different from a non-sinusoidal oscillator. Where, a sinusoidal oscillator produces a sinusoidal waveform by using resonance principle. Whereas, a non-sinusoidal oscillator generates a non-sinusoidal signal by using switching principle. In practice, the signals having non-sinusoidal waveforms are usually generated with the help of multi-vibrators.

For the operation of an oscillator, a source of DC power is required to supply the required operating power. The oscillator uses this DC power to produce a signal of definite frequency in the form of AC power.

Difference between Amplifier and Oscillator

The following table highlights all the noticeable differences between an amplifier and an oscillator:

Basis of Difference	Amplifier	Oscillator
Definition	An electronic circuit that increases the magnitude of a weak signal is called an amplifier.	An electronic circuit that generates an AC signal of definite frequency having either sinusoidal or nonsinusoidal waveform is called an oscillator.
Primary function & location in circuit	The main function of an amplifier is to increase the intensity of a signal. Therefore, the amplifiers are repetitively used in a circuit because the signal losses its energy while travelling over long distances.	The main function of an amplifier is to increase the intensity of a signal. Therefore, the amplifiers are repetitively used in a circuit because the signal losses its energy while travelling over long distances.
Acts as	Amplifier acts as a multiplier.	Oscillator acts as a source.
Output signal	The output of an amplifier is just an amplified signal of same nature as the input. It may be period or aperiodic.	Oscillator always generates an oscillatory, i.e. periodic signal.
Presence of input & output	An amplifier necessarily has both input and output.	An oscillator has only an output.
Substituting	An amplifier can never perform the function of an oscillator.	We may use an oscillator itself in place of amplifier to produce a strong signal.
Feedback	In amplifiers, the negative feedback is used.	Oscillators use positive feedback.
Need of input signal	For the operation, an amplifier necessarily requires an input signal to generate an amplified output signal. Without input signal it does nothing.	Oscillator does not require input signal to generate an oscillatory output signal.
Applications	Amplifiers are widely used in audio systems to increase the intensity of audio signals.	Oscillators are extensively used in computers, laptops, and many other electronic devices and systems to generate the clock pulses for synchronization.

Conclusion

The most significant difference that you should note here is that an amplifier just increases the magnitude of a weak signal to produce an output signal of high intensity, while an oscillator generates an oscillatory signal of a definite frequency. In practical electronic circuits, an oscillator is used at the initial stage of the circuit, while amplifiers are used repetitively at different stages after the oscillator.