Active Spectrum switches gears with wireless

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CAMBRIDGE, Mass. — Active Spectrum Inc. has a bold vision. It wants to kick in the locked doors of wireless communication.

Right now, makers of wireless devices — from military contractors to cellular handset giants like Nokia and Samsung — can only build devices that communicate on a specific frequency. None can talk to devices that use other frequencies, unless they include additional transceivers for those other frequencies.

Picture each device as its own office tower, where users can talk to others in their own towers but not to people in other towers.

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Using MEMS technology, Active Spectrum wants to make a multi-frequency transceiver, and let people start talking to others in any tower they please.

The six-person startup from MIT, still in the midst of incorporating, has taken technology originally designed for a micro-valve and converted it into a small, highly precise capacitor. That capacitor is the heart of a radio-frequency (RF) filter that can be “tuned” as needed to a large range of the wireless spectrum.

“The RF filter is the big limitation factor,” says Othman Laraki, Active Spectrum’s spokesman.

Laraki likens current transceiver technology to automobile engines that only work in one gear. Wireless devices lack a “gear box” to allow them to hopscotch between bands as necessary — so the devices simply cram in more transceivers, like a car with three engines to travel in high, low and reverse gears.

Active Spectrum’s technology sprung from the doctoral thesis of James White, the company’s founder and chief executive officer. Five years ago he began developing a micro-valve to control liquid and gas flows (subsequently sold to NIST) that held two millimeter-sized plates only a few microns apart.

One of White’s mechanical engineering professors, Alex Slocum, noted that coating the plates with gold would create a capacitor suitable for a multi-frequency filter. MIT’s Deshpande Center gave White’s team a $250,000 grant in 2002 to build a prototype.

By adjusting the filter’s plates at angstrom-scale increments, Active Spectrum’s filter essentially allows a transceiver to switch gears. The technology circumvents a principal obstacle for multi-frequency transceivers today: the use of oscillating crystals, which can only vibrate in a narrow frequency range. MEMS omit the crystal and the transceiver can exploit the wider oscillation range that the filter’s physical properties possess.

“It’s completely out of left field relative to the RF world,” Laraki says.

A tunable filter has two logical markets: cellular telephones and the military. Cell phone makers like Nokia and Motorola are scrambling to offer handsets with various capabilities, such as cellular voice service and WiFi data service.

The Defense Department, meanwhile, has more than 25 different RF architectures for its wireless devices — none of which can actually talk to each other.

The challenge for Active Spectrum and its rivals, Cahners In-Stat analyst Allen Nogee says, is cost.

Handset manufacturers “would love it, but they don’t want to pay for it,” Nogee says. Typically, the RF components of a handset cost about $3.50; adding an extra band costs another 50 cents. If the phone-makers could find a solution that matches or improves the $3.50 cost, they’d jump on it.

Laraki, however, styles Active Spectrum as a complementary technology to software-based approaches, to reduce the number of physical components software-based radio still requires. Active Spectrum has done some collaboration with Vanu to explore that idea.

And other technologies are jockeying against Active Spectrum’s MEMS approach, Nogee warned. Texas Instruments, for example, would like to digitize wireless spectrum and then manipulate it with digital-signal processors. Software-defined radio is another concept (Vanu Corp. is chasing this idea), where software virtualizes the transceiver function. But that approach is data-intensive.

“It’s the MEMS guys who stand the best shot at this,” Nogee says.

Laraki says Active Spectrum has not yet decided which market to tackle first, but all signs point to the military; a startup like Active Spectrum simply lacks the scale to work with handset makers and their suppliers. “We’re sure we can’t enter the cell phone market right now,” Laraki even admits.

Active Spectrum has not raised any money yet. Instead, it has courted military agencies such as the Office of Naval Research, and expects to land its first purchase orders by September. Product should start shipping by January, Laraki says, and a round of funding might follow after that.

“We’re not desperate for money, and that’s a good thing,” he said.


Active Spectrum Inc.


Active Spectrum, an MIT offshoot in the process of incorporation, has it origins in the doctoral thesis research of James White, who later became founder and CEO. The company does not yet have independent headquarters.

Industries potentially served

Communications: RF / Wireless

Small tech-related products and services

Active Spectrum is developing a MEMS-based tunable capacitor that will allow wireless applications to communicate across multiple frequencies. By eliminating the need for an oscillating crystal, MEMS technology broadens the frequency range. It is likely that Active Spectrum’s first market foray will be in the defense sector; it is in discussion with the Office of Naval Research, and expects to have product ready to ship in January.


James White, founder and chief executive officer Othman Laraki, spokesman Alexander Slocum Hong Ma Onnik Yaglioglu


Active Spectrum received a $250,000 grant in 2002 from MIT’s Deshpande Center, to aid in their construction of a multi-frequency capacitor prototype.

Selected customers and strategic partners

Office of Naval Research

Selected competitors

Texas Instruments

Vanu Corp.

Barriers to market

Altering existing RF components to include Active Spectrum’s capacitor product means upping the total handset component price by nearly 15% — not feasible for most wireless handset providers. Also, the nascent company is not ready to work with large clients such as cell phone manufacturers. Competing technologies exist, including methods involving digitized wireless frequencies and “virtual” software-driven transceivers.

Contact (US office)


Phone: 617-253-0012

Email: [email protected]

Research by Gretchen McNeely


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