The RF tuner is a major component in a mobile-TV design, and the market for such parts is real. Frontier Silicon reported that it has shipped more than 1 million RF tuners for mobile TV in handsets, and Analog Devices Inc. said it has shipped more than 8 million tuners into the mobile-TV market.

A number of chip suppliers now offer integrated tuner designs that support current mobile-TV standards, including Digital Video Broadcast-Handheld (DVB-H), Digital Multimedia Broadcasting (DMB), ISDB-T and Digital Audio Broadcasting (DAB). Some chips integrate a demodulator with the tuner. Though not comprehensive, the table underscores the bustling design activity surrounding RF tuners. Designers of portable equipment should weigh several key considerations when selecting a mobile-TV tuner, suppliers said.

"The biggest performance issue is the ability to reject both unwanted channels and the GSM carrier, preventing interference that can mar the user experience," said Greg Zancewicz, director of broadband marketing for Microtune Inc. "Broadcast TV stations, cellular transmissions and automotive ignition systems can clutter the airwaves, causing blocky TV pictures, artifacts and lost signals. The primary cause of interference, however, is the mobile device's power amplifier, located only millimeters away from the TV tuner chip."

Linearity is a key consideration for those looking to reject unwanted signals. Designers who simply select the tuner with the best linearity may miss some trade-offs, however. "Do not consider power consumption as the only important aspect, since lower-power tuners are often less linear," cautioned Yannick Levy, CEO of DiBcom. In picking a tuner, it is important to maintain a 1-dB or less noise figure vs. linearity, or overall system performance can degrade.

Balancing noise and sensitivity is also important. "Mobile TVs have a small antenna inside the handset, so the sensitivity of the RF tuner is critical for getting reception in many kinds of environments, such as in buildings and subways," said Brian Ko, general manager of mobile-TV products for Analog Devices Inc. However, as carriers roll out mobile-TV services, many expect that sensitivity will be less of an issue due to an abundance of strong signals.

Designers are already tuned in to the need for low power, small size and low cost, which remain top drivers for innovation in the mobile-TV space. "Size has to be below 10 mm², and thickness needs to be 1.3 or 1.2 mm at the most," said Mark Hopgood, business development director for mobile TV at Frontier Silicon. Hopgood also had a warning for designers adding mobile-TV functionality: Selecting a product that does not offer some margin can be risky, and the headroom will depend upon the standard used.

For instance, DVB-H is benchmarked by the Mobile and Portable DVB-T/H Radio Access Interface (MBRAI) specification. Since network planners rely on these benchmarks, designs without performance margin might miss the mark. DiBcom's Levy suggested that DVB-H designers measure the margin over the MBRAI selectivity pattern (S1, S2) and linearity pattern (L1, L2, L3) tests.

"These MBRAI test patterns include different combinations of digital and analog adjacent channels from N±1 to N±4," he said, suggesting that designers verify the specs themselves and measure the sensitivity over the entire UHF band.

The future of the mobile-TV tuners holds great interest. Some see the market relying heavily on system-in-package (SiP) solutions, while others see a direct path to higher integration.

The need for small size and increased integration is leading a number of RF tuner designers to CMOS. "We have a 1.9-mm² wafer-level chip-scale package that is 0.4 mm thick. You cannot get that in an SiP solution, so you are left with no choice but to go toward CMOS integration," said Kishore Seendripu, CEO of MaxLinear Inc. "There is a misconception that tuners require expensive exotic processes. But CMOS is once again going to win the battle of integration and become the de facto technology."

Some debate the merits of integrating a TV demodulator with the RF tuner. "The tuner and demodulator will be initially integrated into an SiP in the next generation of mobile-TV phones," said Microtune's Zancewicz. "During the next few years, we expect the demodulator to migrate into core digital silicon, such as the application processor. The tuner is expected to remain an independent component or integrate with other RF functions, such as Bluetooth or GPS."

"The biggest misconception regarding RF tuners for mobile TV is that there is a market for standalone tuners in the long term," said Chris Cytera, product-marketing manager for Broadcom Corp.'s mobile-TV products. "Broadcom believes that this market is short-lived and that long-term, the tuner will be integrated with the demodulator."

Regardless of how they are implemented, mobile-TV tuners will have to be multimode and multiband. "Broadcast standards are evolving not just for TV but also for audio, and everyone wants to field the most functional device possible," said Frank Prest, director of the TV and Radio Wireless Business Unit at Maxim Integrated Products Inc. "From the tuner perspective, we want to be ready for everything."

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