This month, Intel unveiled a Wi-Fi radio almost completely made of the same sort of transistors that go into one of its microprocessors.
At the Intel Developer Forum in San Francisco, Yorgis Palaskas, research lead in radio integration at Intel and the company’s chief technology officer, Justin Rattner, also showed off a system-on-a-chip that sported this digital Wi-Fi radio nestled up next to a couple of its Atom processors for mobile devices.
The announcements make it clear that Intel believes Wi-Fi radios—traditionally relatively large devices that operate mostly outside the chip—will be integrated into the chips in coming years. This could mean three things: more electronic devices will be able to network wirelessly; these devices could be more energy-efficient; and ultimately, multiple digital radios could be combined on a single chip, something that could make gadgets, including mobile phones, cheaper.
“We are now looking at moving a lot of the parts on the periphery, like Wi-Fi, into the chip itself,” says Jan Rabaey, professor of electrical engineering and computer science at the University of California, Berkeley. “If wireless can move into digital and miniaturize at the same pace as digital, that’s a good thing.”
All radios, technically called transceivers, are made of a number of components. A transceiver is composed of a receiver that brings in a signal from the outside and a transmitter that sends out a signal to the world. Both receiver and transmitter contain components such as amplifiers to make small signals larger, filters and mixers to select and fine-tune the signal, and a baseband to modulate and demodulate, encode and decode data.
Engineers have, for years, been slowly digitizing these components, so there are fewer analog components, which don’t operate well when miniaturized. Basebands, for instance, have long been digital.
There have already been demonstrations of almost completely digital Bluetooth radios. And Intel itself has digitized important radio components for 3G operation. But radios like Wi-Fi that operate across a wide range of frequencies and have been harder to convert from analog to digital.
While there have been no other public announcements from other companies about digital Wi-Fi radios, it’s likely ARM and Qualcomm are also tackling the challenge, says Rabaey. “You can bet those guys are doing digital structures as well,” he says. “It’s a whole industry trend.”
By making radios using the same process used to make microprocessors, Intel is streamlining manufacturing and making it easier and cheaper to add a Wi-Fi radio to any chip.
“Being able to add this functionality digitally means you can add a radio to pretty much anything you want to,” says Peter Cooney, an analyst at ABI Research. This could allow anything with a chip to communicate, from SD cards and dishwashers to television sets and the family car.
And as chips shrink, Wi-Fi radios will experience the same benefit of miniaturized processors, including a reduction in power consumption (see “A New and Improved Moore’s Law”).
Intel’s Palaskas explains that a digital Wi-Fi radio that takes up 1.2 millimeters of chip space will draw 50 milliwatts of power. The same radio design compressed into an area of 0.3 millimeters (manufactured with so-called 32-nanometer processes) will only sip 21 milliwatts. This is comparable to the best radios made mostly out of analog components, says Palaskas.
But battery life for gadgets themselves is a tricky thing to predict, says Rabaey, and the energy efficiency gained from shrinking transistors might not translate directly to fewer charges for your phone. Much depends on standards that dictate the design of radios. For instance, radios that constantly send signals when they’re not being used directly will drain a battery, no matter how many digital components they contain.
Perhaps the most compelling application of the digital Wi-Fi radio, though, is that it points to a future where more radios can be programmed with software, changing their functionality on the fly. A simple software upgrade to a device with a digital radio could potentially improve its performance. “Digital is fundamentally more programmable than analog,” says Palaskas.
Rabaey suggests that in the future, multiple digital radios could be combined into one, which could reduce the cost of making cell phones. Instead of separate components for 3G, 4G, Wi-Fi, Bluetooth, and other radios, a single chip could contain all of them. The device would flip between radios via software. “Truly programmable radio could be five or 10 years away,” says Rabaey. “But everyone sees the economic value in it.”
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