What is the amplifier?

Short answer:

An amplifier is a device that increases the amplitude of a signal. It is a basic component in many electronic circuits, and is used to increase the power of a signal before it is sent to a load. Amplifiers are classified according to the type of signal they amplify, such as audio, radio, or optical.

• The amplifier is the device that increases the strength of the signal.
• It is used in audio systems to make the sound louder.
• It is also used in other systems, such as radio and TV, to make the signal stronger.

Long answer:

An amplifier is a device that changes the electrical signal input to it into a larger one. It magnifies the input signal. An amplifier may be an electrical circuit that contains only active elements (transistors, diodes and so on), or it may contain both active and passive elements. In the case of the latter, it is combined with a generator of electrical signal in order to provide both amplified and rectified output.

Amplifiers are generally classified according to their gain-frequency characteristics as well as their power-supply requirements. The gain-frequency characteristic can be linear or non-linear. The former means that the amplification provided by an amplifier is constant over a wide range of frequencies, while in the latter this is not the case.

A linear amplifier is one in which the gain stays constant over all frequencies. These are usually described as having high gain, and typically use one or more stages of electromagnets with fixed field strength for amplification. Fixed-frequency power generators are used for generating sinusoidal waveforms at fixed frequencies. If these generators are designed so that they have no appreciable losses, then the overall efficiency will also be high (more than 90%). However, this comes at the expense of reduced flexibility.

Amplifiers with a nonlinear gain-frequency characteristic are generally used if maximum flexibility or efficiency is required. In such amplifiers, both the generator and the amplifying elements can vary greatly over frequency, and additional stages are used to make up for losses in other stages (which cannot usually be made perfect).