The term 'Gain' is a very frequently heard word in electronics. You must have clear knowledge about the term 'Gain' because it required for the understanding of amplifier working principle, transistor characteristics, audio engineering, etc.
Actually, this word first comes when we going to understand the characteristics of a transistor, it may be a BJT(Bipolar Junction Transistor) or a FET(Field Effect Transistor). After it comes when going to understand the capacity, characteristics of an amplifier. So in this article, we are going to discuss What is Gain, what is current gain, voltage gain, and power gain.

## Definition of Gain

In simple words, the gain of any circuit, system, or device is the simple ratio of output to the input of that system, circuit, or device where the output always measured with respect to the input.

Actually, the term 'Gain' comes at the point when the output and input of a system are the same in nature. For example, in an audio amplifier circuit both input and output are the same, means both are audio signal and they have the same frequency, same nature just difference is the output is more powerful than the input. The output is how much powerful than the input, indicates the capacity of that amplifier which is represented by Gain.

The term 'Gain' also sometimes used to represent the responsivity of a system whose input and output have different units. But remember that it mostly used to represent the capacity and characteristics of a system whose input and output have the same unit.

## What is Current Gain?

It is the simple ratio of output current and input current of any circuit, device, etc.
The current gain of a circuit or system indicates that maximum how much current can deliver to the load as output with respect to the particular applied input current.

Example: Generally, the 'Current Gain' word mostly used to understand the amplifying characteristics of a transistor. When we applied a weak signal in its input, it amplified that signal with the help of an external reference power supply and produce a strong amplified signal. To better understand read the article Transistor as an Amplifier

## What is Voltage Gain?

It is the simple ratio of the output voltage to the input voltage of a system or circuit. It indicates that maximum how much output voltage can produce with respect to a particular input voltage.

Example: In the case of Signal amplifier, operational amplifier, audio amplifier, the 'Voltage Gain' term is used because they work on the principle of voltage amplifying.

## What is Power Gain?

It is the simple ratio of output power to the input power of a system or circuit. It indicates the capacity of a circuit to amplify power with respect to the input power.

Example: The term 'Power Gain' generally used to represent the capacity of an RF or Radio Frequency Amplifier. Because RF amplifier works to increase the power of an RF signal to make it stronger for further wireless transmission.

## What is the Unit of Gain?

In general, the Gain has no unit as it is the simple ratio of output and input of a system having the same units. But when we calculate the gain of a system, it always is written with dB or decibels because we use the logarithm technique to calculate the gain of a system. So decibel or dB is not the unit of gain, it indicates the logarithm relationship in a Gain calculation.

As we discussed before, the term 'Gain' sometimes used to represent the responsivity of a system whose input and output have different units. So, in these cases, Gain has a unit. For example, in the case of a Photosensor, the unit of gain is 'microvolts per photon'.

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What is Current Gain and Voltage Gain? Example Reviewed by ETechnoG on 10/20/2020 Rating: 5