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Noise canceler IC suits DVB-H, cellular handsets

Posted: 16 Jan 2007 ?? ?Print Version ?Bookmark and Share

Keywords:noise canceller? DVB-H? handset? cellphone? analog?

Quellan's chips model channel noise in amplitude, phase and frequency dimensions.

When Quellan Inc. introduced high-speed analog signal conditioners for 10Gbit data centers last year, CEO Tony Stelliga promised the company would next bring noise cancellation to consumer platforms. Quellan made good on that promise with Q:Active, extremely small noise-source emulation chips intended for handsets, particularly those for mobile broadcast video.

Borrowing concepts from a wireline noise canceler for 5Gbit links, Q:Active models three dimensions of active noiseamplitude, phase and frequencysubtracting in-band noise from the receiver. Quellan has garnered interest not only from DVB-H handset developers but also from those working on multiband, multimode cellular devices that include GPS location receivers.

Development case
"We had talked to several handset OEMs from the early phases of the company, when we were introducing some of the basic concepts of the collaborative signal-processing architecture," Stelliga said. "But we used noise canceling in wireline environments as a development case for getting the chip size down to the very low footprint and power required for the handset industry."

The designers worked under the assumption that next-generation handsets would include separate RF sources for CDMA, GSM, 802.11, Bluetooth, satellite radio, GPS and DVB, as well as interference sources for the camera and display. Improving camera resolution aggravates the interference problem, Stelliga said. "Some RF/IF chip specialists recognized the need for noise-cancellation solutions in multiband radio, but few had been looking at the combined problem of multiple service bands and camera interference," he said.

Many of Quellan's early demos received high-quality video signals even in areas with weak reception. But the chips carry tangential benefits, such as quick locking on GPS signals, fast handoff between Wi-Fi VoIP and standard cellular services, and a virtual absence of satellite radio dropouts in most terrestrial environments.

Quellan has developed prototypes for 3D portable gaming platforms and is working on versions of Q:Active for the automotive industry.

Quellan will sample two families within Q:Active. The QNx noise-cancellation family can provide 15dB of bulk cancellation from a die measuring less than 1.5mm2. This device will be used as often in bare-die fashion, integrated inside hybrids, as it is in packaged ICs. The QHx harmonic canceler is for in-line insertion with display clocks and drivers handling clock frequencies from 30MHz to 70MHz, and providing 15dB harmonic cancellation.

- Loring Wirbel
EE Times

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