Amplifier Definition

Introduction

An amplifier is electronic equipment that increases an electrical signal's strength and power (or, in scientific terms, amplitude). Without changing its other properties, which are frequency or waveform, an amplifier amplifies a weak input signal into a strong output signal.

The main use of an amplifier machine is to power up a signal strength so that the signal can be sent or passed on over the channel or medium more effectively. Amplifiers are also used in music players to amplify or boost the signal strength of Audio received from the player or microphone to give output in better form.

Amplifiers have a few basic components: an input circuit, an output circuit to send the output, and an amplifying circuit. The major work of an input circuit is to receive a weaker strength of the signal and then an amplifier which basically changes its strength and makes it audible to the human ear, and an output circuit which transfers the amplified signal or Audio to a load which may be a speaker sometimes.

Gain is a term used to measure the degree of amplification done by an amplifier or how much it increases the amplifier's power. The SI unit for measurement of the gain of an amplifier is decibels or DB.

The amplification process uses active components, like vacuum tubes, operational amplifiers, or transistors, that may increase the amplitude or intensity of the incoming signal. The most common unit of measurement for amplification levels in decibels (dB). This logarithmic unit compares the signals at the input and output. Operational amplifiers (op-amps), voltage, current, and power amplifiers are only a few examples of amplifiers' wide varieties and designs. Every amplifier type has distinct qualities and characteristics that make it the best choice for that job.

Type of Amplifiers

Several amplifiers are designed for specific applications and with unique characteristics. Some common types of amplifiers include:

1. Voltage amplifier

Voltage amplifiers are electrical devices that increase the voltage of an input signal. Small items may be made larger by using them as magnifying glasses. Electronic circuits frequently use weak, tiny signals. A voltage amplifier is needed to strengthen them for other circuit components.

Think of getting a little electric guitar with a thin tone. Even if you don't want to utilize a larger guitar, you still want to play the instrument louder. You can also connect the guitar to a voltage amplifier to increase the sound's volume. The amplifier receives the little signal from the guitar and amplifies it to produce a larger signal. Now, the guitar is more audible and distinct.

The voltage amplifier generates amplification using transistors or operational amplifiers (op-amps). These components boost the input signal's voltage without altering its frequency or shape. Voltage amplifiers have in-built gain settings by which we can change the degree of voltage to be amplified, which can affect how much the signal is amplified.

Like, suppose we change the degree of gain to 10. In that case, the amplifier will amplify the signal ten times stronger; if the input signal is 1 volt, it will be 10 volts after amplification. Similarly, if set to 100, the signal would be 100 times stronger.

Just like guitars and other electronic musical instruments, Audio devices, radios, and TVs also need amplifiers to power up and output Audio in better quality. They are also utilized in scientific and industrial applications to enhance signals from sensors or equipment.

2. Current Amplifier

A current amplifier is an electrical device to boost the amount of electric current flowing through a circuit. A lower electric current is the input signal, while a bigger one is the output. A current amplifier's function is to increase the input signal's power so that other circuit components may use it.

Understanding how a current amplifier operates makes visualizing a water hose easier. Some water trickles through a water hose when it is just partially turned on. But adding a pump to the hose can improve the water flow. A current amplifier operates according to similar principles. It "pumps up" the circuit's electric current.

Current amplifiers are extensively used in scientific and engineering applications, such as medical equipment or sensors measuring temperature or pressure. They can be used in audio systems to boost the signal from a microphone or other source.

A current amplifier manages the current flow across a circuit by a transistor or another electrical component. This amplifier is designed uniquely so that the base of the transistor connects the input signal, and the collector or emitter of the transistor is connected to the output signal. Here, transistors may act like a switch or a valve that allows current flow through the circuit.

Gain, a measure of how much the output current is raised compared to the input current, determines how much amplification a current amplifier offers. By changing the component values in the circuit, a current amplifier's gain may be altered.

3. Power Amplifier

The power amplifier is a type of amplifier that is the most basic type of amplifier and is also used to increase the strength of an electric signal. Power amplifiers are used in speakers, high-power devices, or musical instruments to give a better and enhanced audio output. These amplifiers are used frequently in Bluetooth devices, home theatres, and music places.

Let's use a guitar amplifier as an example to better grasp how a power amplifier functions. The signal coming from the pickups on an electric guitar is often quite faint when played. The signal must be amplified to be audible at a suitable volume. A preamp stage of a guitar amplifier raises the signal's level so that the power amplifier may amp it up even further.

The power amplifier in a guitar amplifier boosts the preamplified signal's power to a level where it can drive the speaker. To do this, a transistor or other electronic component manages the circuit's current flow. The base of the transistor receives the input signal, while the collector or emitter receives the output signal. In this amplifier, the transistor is designed in the same manner as in the voltage amplifier; the input signal is the most crucial part and gets received by the base of the transistor, and the emitter or collector is made at the upper part and is used to receive the output signal.

The gain or the amount of power of a guitar amplifier is measured in watts as well. The sound that may be generated increases in volume as wattage increases. A huge concert amp could have a power rating of 1000 watts or more, while a modest practice amp would only have a power rating of 10.

Power amplifiers are also used in various audio systems, including DJ gear, home theatre, and live sound reinforcement systems. The power amplifier drives the speakers or other sound-producing equipment in these applications.

4. Operational amplifier

An electrical device known as an operational amplifier (op-amp) amplifies an input signal to create an output signal. It is a particular class of voltage amplifiers with a very high gain that may be included in several circuits, including filters, oscillators, and comparators.

Let's think about an example to grasp better how op-amp functions. Consider yourself in possession of a speaker and a microphone. When you talk into it, the microphone generates a small electrical signal delivered to the speaker. However, the signal must be amplified because it is too faint to be heard properly.

Amplification of the microphone signal is possible using an op-amp. The output signal is obtained from the op-amp's output, and the input signal is linked to the non-inverting input of the op-amp. The op-amp amplifies the signal by a large factor controllable by feedback resistors.

For instance, if the op-amp's gain is set to 10, a 1-volt input signal will result in a 10-volt output signal. As a result, the op-amp can amp up a weak signal to a level where a speaker can hear it.

Op-amps may also be employed in comparators, electronic devices that compare two input signals and generate an output signal based on the comparison results. An op-amp comparator, for instance, might be used to determine if a battery is completely charged, partially charged, or needs to be recharged by comparing its voltage to a reference value.

Op-amps can also be used in filters, circuits that selectively pass or block particular frequencies of an input signal, in addition to amplification and comparison. An op-amp filter, for instance, might be used to eliminate noise from a signal or to extract particular frequencies from a complicated signal.

5. Class A amplifier

An electronic amplifier noted for its strong linearity and minimal distortion is called a "Class A" amplifier. The output stage of the amplifier functions in such a way that the output transistor(s) are always "on" and conducting current, even in the absence of an input signal, which is why it is termed a "Class A" amplifier.

Let's look at a straightforward Audio amplifier with a single transistor as an example to grasp better how a "Class A" amplifier functions. The input signal is supplied to the transistor's base in this amplifier, and the output signal is obtained from the collector. The transistor emits a continuous current known as the "quiescent current" when there is no input signal.

The transistor's conductivity changes in response to an input signal applied to the base, which changes the collector current. Due to the transistor's amplification, the output signal is a copy of the input signal with a greater amplitude.