Rf power amplifier
Encyclopedia
An RF power amplifier is a type of electronic amplifier
used to convert a low-power radio-frequency signal
into a larger signal of significant power, typically for driving the antenna of a transmitter
. It is usually optimized to have high efficiency, high output Power(P1dB) compression
, good return loss on the input and output, good gain
, and optimum heat dissipation.
, microwave heating, and exciting resonant cavity structures. Among these applications, driving transmitter antennas is most well known. The transmitter–receivers are used not only for voice and data communication but also for weather sensing (in the form of a RADAR
). Microwave or RF heating is an industrial application which is also benefiting our homes in the form of microwave oven
s. Exciting cavity resonator
s is quite a research lab and industrial application of an RF source. Particle accelerator
s utilize RF sources extensively.
transformations over large bandwidth are difficult to realize, thus most wideband
amplifier
s use 50 Ω output loading. Transistor
output power is then limited to
is defined as the breakdown voltage
is defined as the knee voltage
and
Electronic amplifier
An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...
used to convert a low-power radio-frequency signal
Signal (electrical engineering)
In the fields of communications, signal processing, and in electrical engineering more generally, a signal is any time-varying or spatial-varying quantity....
into a larger signal of significant power, typically for driving the antenna of a transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
. It is usually optimized to have high efficiency, high output Power(P1dB) compression
Signal compression
In telecommunication, the term signal compression has the following meanings:In analog systems, reduction of the dynamic range of a signal by controlling it as a function of the inverse relationship of its instantaneous value relative to a specified reference level.Signal compression is usually...
, good return loss on the input and output, good gain
Gain
In electronics, gain is a measure of the ability of a circuit to increase the power or amplitude of a signal from the input to the output. It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. It may also be defined on a logarithmic scale,...
, and optimum heat dissipation.
Applications
The basic applications of the RF power amplifier include driving to another high power source, driving a transmitting antennaAntenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
, microwave heating, and exciting resonant cavity structures. Among these applications, driving transmitter antennas is most well known. The transmitter–receivers are used not only for voice and data communication but also for weather sensing (in the form of a RADAR
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
). Microwave or RF heating is an industrial application which is also benefiting our homes in the form of microwave oven
Microwave oven
A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
s. Exciting cavity resonator
Resonator
A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical...
s is quite a research lab and industrial application of an RF source. Particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
s utilize RF sources extensively.
Wideband amplifier design
ImpedanceElectrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...
transformations over large bandwidth are difficult to realize, thus most wideband
Wideband
In communications, wideband is a relative term used to describe a wide range of frequencies in a spectrum. A system is typically described as wideband if the message bandwidth significantly exceeds the channel's coherence bandwidth....
amplifier
Amplifier
Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
s use 50 Ω output loading. Transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
output power is then limited to
is defined as the breakdown voltage is defined as the knee voltageand