Freescale Introduces High-Power, High-Efficiency UHF LDMOS Transistor

At the NAB Show, several transmitter manufacturers were showing new UHF solid-state DTV power amplifiers that were more efficient, cost less and occupied less space. Axcera showed a 10 kW average output power solid-state DTV transmitter in one rack. The transistors were covered so it wasn’t possible to determine what devices they were using. The transmitter should be available later this year. While amplifier design, choice of materials and combining systems can increase power and improve efficiency, there is at least one new transistor that could make it easier for manufacturers meet these goals.

Transmitter engineers are used to seeing tube companies at NAB and you may remember the Cray Semiconductor display of amplifiers using silicon-carbide transistors several years ago. This year, Freescale Semiconductor introduced an LMDOS RF power transistor capable of delivering up to 450 watts peak output per device. Freescale claimed its MRF6VP3450H offered “the highest output power in its class for UHF applications,” along with reduced power requirements that could potentially save users “thousands of dollars” in power bills.

Typical power gain in DVB-T operation at 50 V is 23 dB, with a drain efficiency of 28 percent and an average power output of 90 W. The output power would be higher for ATSC, which has a lower peak to average ratio than DVB-T. The transistor is capable of handling a 10:1 VSWR at 50 VDC and is designed for push-pull operation.

“As energy costs continue to soar, the ability to use highly efficient, cost-effective TV transmitters is critical to broadcasters,” said Gavin Woods, vice president and general manager of Freescale’s RF Division. “Transmitters designed with our new MRF6VP3450 device not only deliver dramatic annual energy savings, but also can significantly reduce transmitter cost by helping to minimize the number of required RF power transmitters.”

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. As vice president of Broadcast Technology for NBCUniversal Local, H. Douglas Lung leads NBC and Telemundo-owned stations’ RF and transmission affairs, including microwave, radars, satellite uplinks, and FCC technical filings. Beginning his career in 1976 at KSCI in Los Angeles, Lung has nearly 50 years of experience in broadcast television engineering. Beginning in 1985, he led the engineering department for what was to become the Telemundo network and station group, assisting in the design, construction and installation of the company’s broadcast and cable facilities. Other projects include work on the launch of Hawaii’s first UHF TV station, the rollout and testing of the ATSC mobile-handheld standard, and software development related to the incentive auction TV spectrum repack.
A longtime columnist for TV Technology, Doug is also a regular contributor to IEEE Broadcast Technology. He is the recipient of the 2023 NAB Television Engineering Award. He also received a Tech Leadership Award from TV Tech publisher Future plc in 2021 and is a member of the IEEE Broadcast Technology Society and the Society of Broadcast Engineers.