Freescale sets new benchmark with RF power LDMOS transistor for broadcast TV transmitters

AUSTIN, USA: Freescale Semiconductor has introduced an RF power LDMOS transistor that combines the industry’s highest output power and efficiency with the greatest ruggedness of any competitive device in its class designed for UHF broadcast television applications.

The latest addition to Freescale’s family of RF power LDMOS transistors, the MRFE6VP8600H, delivers 39 percent greater output power than its predecessor and is designed to deliver maximum performance for many key digital transmission standards including ATSC, DVB-T and ISDB-T. The MRFE6VP8600H provides significant benefits for television transmitter manufacturers and broadcasters. For example, the transistor delivers 125W of linear power (more than 600W peak envelope power) over the entire broadcast band, with exceptional efficiency (typically 30 percent at 860 MHz and up to 45 percent when employed in a Doherty configuration).

The UHF frequency band ranges from 470 MHz to 860 MHz and is used by broadcasters to transmit television signals over the air. The vast majority of television stations currently broadcasting in digital are using the UHF band.

“The new MRFE6VP8600H reinforces Freescale’s continued commitment to delivering the outstanding performance and efficiency our customers need to thrive, even within industries facing extremely stringent market requirements,” said Ritu Favre, VP and GM of Freescale’s RF Division. “This new offering additionally underscores Freescale’s hallmark of leveraging its deep understanding of networking markets to generate performance and efficiency gains via intelligent, system-level design processes.”

The MRFE6VP8600H’s higher RF output and greater efficiency enable a reduction in the total number of transistors and combiner stages needed for a given output power, helping to simplify transmitter design and improve reliability when compared to previous generation solid-state systems. A transmitter based on the MRFE6VP8600H can use up to 15 percent less power than previous generations, leading to substantial operating cost savings.

The MRFE6VP8600H is the most rugged RF power LDMOS transistor in its class. When driven to its full rated RF output power, this device will not degrade in performance when driving an impedance mismatch (VSWR) greater than 65:1, at all phase angles, or when driven by twice its rated input power. The transistor’s ruggedness makes it far more reliable under adverse conditions such as antenna icing, transmission line failure or operator error, even with drive peaks created by predistortion systems.

In addition, the MRFE6VP8600H easily tolerates the out-of-band reflective load conditions caused by highly selective channel filters and the high peak-to-average ratio (PAR) characteristic of digital transmission schemes employing higher-order modulation techniques such as DVB-T (8k OFDM). The enhanced ruggedness characteristics of the MRFE6VP8600H also make it possible to employ simplified transmitter protection circuits.

Key specifications of the MRFE6VP8600H include:
* 125W average RF output power (DVB-T [8k OFDM] signal) at 860 MHz, gain of 19.3 dB and efficiency of 30 percent.
* 600W peak RF power.
* Can be designed into Class AB, Doherty or drain modulation amplifier architectures, eliminating the need for a specific device optimized for each architecture.
* Integrated electrostatic discharge (ESD) protection to provide resistance to stray voltages encountered during assembly.
* Extended negative gate-source voltage range of -6V to +10V to improve performance when operated as the peaking stage of a Doherty amplifier.
* Housed in Freescale’s NI-1230 bolt-down ceramic air cavity package (MRFE6VP8600H) or NI-1230S solder-attach ceramic air cavity package (MRFE6VP8600HS).