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LDMOS (laterally-diffused metal-oxide semiconductor) [1] is a planar double-diffused MOSFET (metal–oxide–semiconductor field-effect transistor) used in amplifiers, including microwave power amplifiers, RF power amplifiers and audio power amplifiers. These transistors are often fabricated on p/p+ silicon epitaxial layers. The fabrication of LDMOS devices mostly involves various ion-implantation and subsequent annealing cycles. [1] As an example, The drift region of this power MOSFET is fabricated using up to three ion implantation sequences in order to achieve the appropriate doping profile needed to withstand high electric fields.


The silicon-based RF LDMOS (radio-frequency LDMOS) is the most widely used RF power amplifier in mobile networks, [2] [3] [4] enabling the majority of the world's cellular voice and data traffic. [5] LDMOS devices are widely used in RF power amplifiers for base-stations as the requirement is for high output power with a corresponding drain to source breakdown voltage usually above 60 volts. [6] Compared to other devices such as GaAs FETs they show a lower maximum power gain frequency.

Manufacturers of LDMOS devices and foundries offering LDMOS technologies include TSMC, LFoundry, Tower Semiconductor, GLOBALFOUNDRIES, Vanguard International Semiconductor Corporation, STMicroelectronics, Infineon Technologies, RFMD, Freescale Semiconductor, NXP Semiconductors, SMIC, MK Semiconductors, Polyfet and Ampleon.


The invention of the metal–oxide–semiconductor field-effect transistor (MOSFET) by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959 was a breakthrough in power electronics. Generations of power MOSFETs enabled power designers to achieve performance and density levels not possible with bipolar transistors. [7] In 1969, the DMOS (double-diffused MOSFET) with self-aligned gate was first reported by Y. Tarui, Y. Hayashi and Toshihiro Sekigawa of the Electrotechnical Laboratory (ETL). [8] [9]

In 1977, Hitachi introduced the LDMOS, a planar type of DMOS. Hitachi was the only LDMOS manufacturer between 1977 and 1983, during which time LDMOS was used in audio power amplifiers from manufacturers such as HH Electronics (V-series) and Ashly Audio, and were used for music, high-fidelity (hi-fi) equipment and public address systems. [10]


In the early 1990s, RF LDMOS (radio-frequency LDMOS) was introduced, as RF power amplifiers for cellular network infrastructure. They eventually displaced RF bipolar transistors, because RF LDMOS provided superior linearity, efficiency and gain along with lower costs. [11] [4] With the introduction of the 2G digital mobile network, LDMOS became the most widely used RF power amplifier technology in 2G and then 3G mobile networks. [2] By the late 1990s, the RF LDMOS had become the dominant RF power amplifier in markets such as cellular base stations, broadcasting, radar, and Industrial, Scientific and Medical band applications. [12] LDMOS has since enabled the majority of the world's cellular voice and data traffic. [5]

In the mid-2000s, RF power amplifiers based on single LDMOS devices suffered from relatively low efficiency when used in 3G and 4G (LTE) networks, due to the higher peak-to-average power of the modulation schemes and CDMA and OFDMA access techniques used in these communication systems. In 2006, the efficiency of LDMOS power amplifiers was boosted using typical efficiency enhancement techniques, such as Doherty topologies or envelope tracking. [13]

As of 2011, RF LDMOS is the dominant device technology used in high-power RF power amplifier applications for frequencies ranging from 1  MHz to over 3.5  GHz, and is the dominant RF power device technology for cellular infrastructure. [11] As of 2012, RF LDMOS is the leading technology for a wide range of RF power applications. [4] As of 2018, LDMOS is the de facto standard for power amplifiers in mobile networks such as 4G and 5G. [3] [5]


Common applications of LDMOS technology include the following.


Common applications of RF LDMOS technology include the following.

See also

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Microwave Form of electromagnetic radiation

Microwaves are a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter; with frequencies between 300 MHz (1 m) and 300 GHz (1 mm). Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF bands. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz. In all cases, microwaves include the entire SHF band at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations.

Transistor Basic electronics component

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

Wireless network any network at least partly not connected by physical cables of any kind

A wireless network is a computer network that uses wireless data connections between network nodes.

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Ultra high frequency The range 300-3000 MHz of the electromagnetic spectrum

Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications.

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