An amplifier is an electronic device or circuit that increases the voltage, current, or power of a signal
. It is used in various applications, including wireless communications, broadcasting, and audio equipment
. Amplifiers can be categorized into two main types:
- Weak-signal amplifiers : These are used primarily in wireless receivers and have a high sensitivity to deal with small input signals, sometimes measuring only a few nanovolts
. The most effective device for this application is the field-effect transistor (FET)
- Power amplifiers : These are used in wireless transmitters, broadcast transmitters, and hi-fi audio equipment
. The most frequently-used device for power amplification is the bipolar transistor, but vacuum tubes (valves) are also gaining popularity, especially among musicians
. Power output and efficiency are important considerations in power amplification
Amplifiers are essential in modern electronics and are widely used in various electronic equipment
. They can be classified based on the frequency of the electronic signal being amplified, such as audio amplifiers for audio signals and RF amplifiers for radio frequency signals
. The performance of an amplifier is measured by its gain, which is the ratio of output voltage, current, or power to input
