Difference between Amplifier and Repeater

The major difference between amplifier and repeater is that an amplifier amplifies the weak signal and the noise associated with this signal also gets amplified. On the contrary, the repeater does not amplify the noise signal. Although a receiver also consists of an amplifier in it but apart from this it also possess a signal reshaping circuit which reshapes the distorted signal and amplifies the undistorted signal.

One may think why these amplifiers and repeaters are used in electronic circuits. To understand the relevance of these circuits in electronics domain, we need to understand the concept of transmission of the signal from the transmitter to receiver.

When the signal is transmitted from a transmitter, it undergoes distortion; this is because interference due to noise signal get introduced in the transmission path.  As a consequence of this noise addition, the information wrapped with the electronic signal also gets modified. This is an undesirable event which makes the communication system less reliable.

To deal with the above problem, we need a circuit which can make this weak signal an amplified one so that it can reach the receiver end without losing any part of the information. The circuit used is nothing but amplifier and receiver. Though both these circuit performs the same operation but due to some constructional features, there exists some difference.

Let’s have a look at the roadmap of this article, after this; we will discuss comparison chart.

Contents: Amplifier and Repeater

1. Comparison Chart
2. Definition
3. Key Differences
4. Conclusion

Comparison Chart

Parameter	Amplifier	Repeater
Definition	The Amplifier is used for the enhancement of the amplitude of the weak signal.	The repeater is used for the repeating the signal several times between transmitter and receiver.
Noise elimination	Amplifier amplifies the noise signal along with the information signal; this makes the resultant signal more noisy.	Repeaters reshape the signal and thus noise elimination is effective in case of repeaters.
Usage in particular domain	Amplifiers are used mostly in communication systems which involves analog signal.	Repeaters are used for repeating digital signal.
Installation distance	The distance between two amplifiers can be large enough as analog signals do not dissipate quickly.	The repeaters are needed frequently because the digital signals dissipate fast in comparison to that of analog signals. Thus, number of repeaters required in communication system will be more than the number of amplifiers.

Definition

Amplifiers

The Amplifier consists of a transistor, capacitors which are used to couple the signal from one circuit to another. The energy required by the amplifier to amplify the distorted signal is transferred to it by the DC power source.

The input signal coming from the transmitter is fed to the amplifier which uses the internal circuitry of transistor and capacitors to raise the amplitude of the input signal. This amplified signal is transmitted to another amplifier which raises the amplitude again. And in this way, the amplified signal is transmitted to the receiver via various amplifiers.

The amplifier is often termed as a single stage and multistage amplifier depending on the use of transistors. If a single transistor is used in the amplifier circuit, then it is known as single stage amplifier. And if multiple transistors are used, then the amplifier is said to be a multistage amplifier.

The amplifiers can also be classified into various types on the basis of the frequency of operation. The amplifier which works in the range of voice frequencies is used for the amplification of voice signals. Similarly, optical amplifiers also come into the picture when we are dealing with the amplification of optical signals.

Repeater

The repeater repeats the signal from the transmitter and supplies it to another repeater with high power gain. The repeater also consists of the amplifier circuit. Moreover, the repeaters can be designed according to the nature of the communication system. In optical communication, we need repeaters with a photodetector and other light sensitive equipment. On the other hand, if we are dealing with electromagnetic signals, then we need antennas, waveguides etc. for the regeneration of the signal.

A repeater is a crucial device in the digital communication system as it is best in handling digital signals. You might be thinking what so makes a repeater a significant device that it is reliable to use in digitals communication systems?

The answer to the above question is that a repeater is much more than an amplifier because it consists of a reshaping circuit in addition to an amplifier circuit. Now, just think about a communication system which amplifier the weak signal by providing high power gain. Besides, before this amplified signal reaches the destination, it is reshaped by a circuit in the repeater.

This reshaping phenomenon is something which makes the repeater a better choice in digital communication systems.

Conclusion

It would not be wrong to say that amplifiers and repeaters are the heart of communication system. The reliability of communication system is totally dependent on the fact that the information from the transmitter is conveyed to the receiver without any modification or distortion.

But if we analyse the practical scenario, we will come across the fact that there are certain constraints in the channel. Due to this, the signal gets deteriorated. Therefore, we need circuits in the mid of the channel to deal with this deterioration. And amplifiers and repeaters best serve this purpose.