RF power amplifier

[1] Typically, RF power amplifiers are used in the final stage of a radio transmitter, their output driving the antenna.

RF amplifier circuits operate in different modes, called "classes", based on how much of the cycle of the sinusoidal radio signal the amplifier (transistor or vacuum tube) is conducting current.

Operating the active device as a switch results in higher efficiency, theoretically up to 100%, but lower linearity.

Modern RF power amplifiers use solid-state devices, predominantly MOSFETs (metal–oxide–semiconductor field-effect transistors).

Although mechanically robust, transistors are electrically fragile – they are easily damaged by excess voltage or current.

[4][10][6] LDMOS-based RF power amplifiers are widely used in digital mobile networks such as 2G, 3G,[4][6] and 4G[10] and the good cost/performance ratio make them the preferred option for amateur radio.

[11] Impedance transformations over large bandwidth are difficult to realize, so conventionally, most wideband amplifiers are designed to feed a 50 Ω output load.