Freescale LDMOS RF Power Transistors Optimize Performance of Wireless Base Stations Using Doherty Amplifiers

(Product News, 5 Jun 2007)

Freescale Semiconductor has released seven LDMOS RF power transistors that deliver exceptional performance and enable WCDMA and CDMA2000 base station transmitters to exploit the full potential of the Doherty amplifier architecture.

Fast becoming an industry standard, the Doherty architecture offers exceptional efficiency but presents design challenges due to conflicting requirements for both high efficiency and high linearity. Designed specifically for the architecture, the new Freescale transistors successfully address these challenges, thereby enabling the creation of base stations that consume significantly less power than those using traditional transistor designs.

Two of the devices operate in the 865MHz to 960MHz band, two in the 1930 to 1990 band, and three in the 2110MHz to 2170MHz band, covering the most popular cellular, PCS and WCDMA frequencies.

The new devices include:

MRFE6S9205H/HS
865MHz to 960MHz, 58W average output power, 20.5dB gain, 34 percent efficiency, ACPR of -38dBc (5-MHz offset, 3.84MHz channel)

MRFE6S9135H/HS
865MHz to 960MHz, 39W average output power, 20dB gain, 34.5 percent efficiency, ACPR of -38dBc (5-MHz offset, 3.84MHz channel)

MRF6S19200H/HS
1,930MHz to 1,990MHz, 58W average output power, 17.2dB gain, 29.5 percent efficiency, ACPR of -38dBc (5-MHz offset, 3.84MHz channel)

MRF6S19140HR3/HSR3
1,930MHz to 1,990MHz, 29W average output power, 16dB gain, 27.5 percent efficiency, ACPR of -51dBc (885kHz offset, 30kHz channel)

MRF7S21170HR3/HSR3
2,110MHz to 2,170MHz, 50W average output power, 16dB gain, 31 percent efficiency, ACPR of -37dBc (5-MHz offset, 3.84MHz channel)

MRF6S21190HR6
2,110MHz to 2,170MHz, 54W average output power, 16.4dB gain, 30 percent efficiency, ACPR of -38dBc (5-MHz offset, 3.84MHz channel)

MRF6S21140HR3/HSR3
2,110MHz to 2,170MHz, 30W average output power, 15.5dB gain, 27.5 percent efficiency, ACPR of 41dBc (5-MHz offset, 3.84MHz channel)

Available on tape and reel, all of the devices operate from a +28V supply and feature integral ESD protection. They are designed to handle a 5:1 VSWR without damage and are housed in RoHS compliant, high-thermal-conductibility air-cavity ceramic packages.

"The Doherty amplifier's inherent high efficiency can help reduce a base station¡¯s annual power consumption when compared to other amplifier types, thus allowing Freescale to deliver to our service provider customers the least costly product to operate," said Gavin P. Woods, vice president and general manager of Freescale's RF Division. "But to achieve its full potential, Doherty amplifiers require RF power devices specifically tailored for their needs. Freescale is the first company to deliver these Doherty-optimized, high-efficiency power devices, which are designed from the ground up to make the most of this unique type of amplifier architecture."

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