Power Transistors Target Doherty Architecture In Basestations

A line of seven LDMOS RF power transistors from Freescale Semiconductor specifically targets WCDMA and cdma2000 basestation transmitter applications that employ the Doherty architecture, which is 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 transistors successfully address these challenges, enabling the creation of basestations that consume significantly less power than those using traditional transistor designs. Available on tape and reel, all of the devices operate from a +28-V supply and feature integral electrostatic discharge protection. They can handle a 5:1 voltage standing-wave ratio without damage and are housed in RoHS-compliant, high-thermal-conductibility air-cavity ceramic packages. Data sheets and a Doherty reference design are available from Freescale for evaluation purposes.

The new devices include:

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

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

o MRF6S19200H/HS: 1930 to 1990 MHz, 58-W average output power, 17.2-dB gain, 29.5% efficiency, ACPR of –38 dBc (5-MHz offset, 3.84-MHz channel)

o MRF6S19140HR3/HSR3: 1930 to 1990 MHz, 29-W average output power, 16-dB gain, 27.5% efficiency, ACPR of –51 dBc (885-kHz offset, 30-kHz channel)

o MRF7S21170HR3/HSR3: 2110 to 2170 MHz, 50-W average output power, 16-dB gain, 31% efficiency, ACPR of –37 dBc (5-MHz offset, 3.84-MHz channel)

o MRF6S21190HR6: 2110 to 2170 MHz, 54-W average output power, 16.4-dB gain, 30% efficiency, ACPR of –38 dBc (5-MHz offset, 3.84-MHz channel)

o MRF6S21140HR3/HSR3: 2110 to 2170 MHz, 30-W average output power, 15.5-dB gain, 27.5% efficiency, ACPR of –41 dBc (5-MHz offset, 3.84-MHz channel)