What type of device is designed to increase the level of its input signal?

An amplifier is a device specifically designed to increase the level of an input signal. It performs this function by taking a weak electrical signal and boosting its strength to a more useful level. This is crucial in various applications, including audio equipment, communication devices, and broadcasting, where weak signals need to be amplified to ensure clarity and reach.

Amplifiers can work with various signal types, including audio, radio frequency, and video signals, and they might operate in different configurations such as voltage, current, or power amplification depending on the specific application. The amplification process involves applying external power to achieve the desired output level, making it a fundamental component in many electronic circuits.

In contrast, an oscillator generates a periodic signal and doesn’t amplify. The term "ampere" refers to a unit of electric current and does not describe a device. A transformer, on the other hand, is used primarily to change the voltage level of an alternating current signal but does not amplify the signal; instead, it transfers energy between circuits through electromagnetic induction.