rf power amplifiers

For the British rock band of the same name, see Amplifier (band)

An amplifier can be considered to be any device that uses a small amount of energy to control a source of a larger amount of energy, although the term today usually refers to an electronic amplifier. The relationship of the input to the output of an amplifier — usually expressed as a function of the input frequency — is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain.

General characteristics of amplifiers

Most amplifiers can be characterised by a number of parameters.

Gain

How much an amplifier increases the signal level is called the gain. This is usually measured in decibels (dB). Mathematically speaking, the gain is equal to the output level divided by the input level. Schaffner Holding AG - International leader in electromagnetic compatibility (EMC), focusing on high-growth sectors. (for power gain in decibels gain is computed by the relation G(dB)=10log(Pout/Pin)(Electrical)).

Output dynamic range

This is the range usually quoted in dB between the lowest useful output and the largest useful output level. Since the lowest useful level is limited by output noise, this is quoted as the amplifier dynamic range.

Bandwidth and rise time

The bandwidth (BW) of an amplifier is usually defined as the difference between the lower and upper half power points. This is therefore also known as the −3 dB BW.