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Freescale Delivers 50 V RF LDMOS Power Transistor

Freescale Semiconductor introduced an RF LDMOS power transistor designed for operation from 1.8 to 600 MHz and optimized for use under the potentially-destructive impedance mismatch conditions encountered in applications such as CO2 lasers, plasma generators, and magnetic resonance imaging (MRI) scanners. The new MRFE6VP6300H FET is the world’s first 50 V LDMOS transistor to deliver full-rated output power of 300 W CW into a load with a Voltage Standing Wave Ratio (VSWR) of 65:1.

All solid-state RF power amplifiers operate most effectively when the greatest amount of power generated by their RF power transistors reaches the antenna. Under ideal conditions, this would result in a VSWR of 1:1, with all of the generated rated power reaching the load via the transmission line with none reflected back to the amplifier. VSWR levels in most applications rarely exceed 2.5:1 and most RF power transistors regardless of their technology can handle a VSWR of 5:1 or 10:1.

However, RF power amplifiers used to ignite CO2 lasers and plasma generators, or to create an electromagnetic field in MRI systems, briefly encounter conditions in which nearly all of their generated rated power is reflected back to the amplifier. These extreme conditions present challenges for most RF power transistors.

Freescale’s new MRFE6VP6300H LDMOS FET was designed primarily to serve these applications and offers the ability to produce its full 300 W of CW output power into a VSWR as high as 65:1. It is the only 50 V LDMOS transistor commercially offered with this level of performance.

“This outstanding technical achievement underscores Freescale’s long track record of industry firsts in the RF power market,” said Gavin Woods, vice president and general manager of Freescale’s RF Division. “With this new transistor, manufacturers of CO2 lasers, plasma generators, MRI scanners and other industrial equipment can leverage unprecedented levels of ruggedness and RF power performance.”

The MRFE6VP6300H can be used in a push-pull or single-ended configuration and is housed in a compact air cavity ceramic NI780-4 package. At 130 MHz, the device produces 300 W of CW output power with 25 dB of gain and 80 percent efficiency. The MRFE6VP6300H also contains innovative electrostatic discharge (ESD) protection that makes it a Class III device while allowing for ample gate-source voltage range (-6V to +10V), enhancing performance when operating in high-efficiency modes such as Class C.

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