Electronic Design

Diverse Component Trio Represents This Year's Best

The components market always seems to be in a state of accommodation, creating products to support every other sector’s designs. Whether it’s a power source that fits an oddly shaped printed-circuit board (PCB) or a motor that can deliver massive torque levels in a space the width of a finger, component makers innovate for innovators.

Over the past year, for example, OmniVision gave digital-camera designers a leg up in their work with its BSI CMOS image sensor, enabling them to create even smaller products while boosting image quality. The LED gurus at Osram Opto Semiconductors claimed a new record for white-LED brightness. And, assembly specialist Spiralock offered large-system developers new hope for ensuring product durability, stability, and reliability while promoting space savings.

CMOS IMAGE SENSOR DOES A BACKFLIP
With the help of chipmaker Taiwan Semiconductor, OmniVision Technologies turned digital imaging upside down in June 2008. Forsaking the usual path that’s taken in CMOS-sensor circles, OmniVision introduced its OmniBSI architecture—a radical sensor design that exploits backside illumination (BSI) to boost image quality while simultaneously shrinking overall pixel sizes down to 0.9 µm. In essence, the new technology addresses the demands for better picture quality in ever smaller and more featurepacked cameras.

Contrary to traditional frontside illumination (FSI) CMOS image sensors, the OmniBSI architecture literally turns the sensor chip upside down. Consequently, it accepts light from what was the backside of the silicon substrate.

With FSI sensors, the metal and dielectric layers necessary for the sensor to convert photons into electrons partially impedes light hitting the photosensitive area. Conventional FSI devices can also block or deflect light from reaching the pixel, which reduces the fill factor and can cause problems such as pixel crosstalk.

OmniBSI reverses the arrangement of layers, situating the metal and dielectric layers under the sensor array so light hits the silicon layer unimpeded (Fig. 1). Thus, the sensor’s fill factor improves and thereby increases low-light sensitivity significantly.

In addition to optimizing light absorption, the BSI arrangement creates a 1.4-µm pixel, a feat OmniVision claims surpasses all performance metrics of most 1.75-µm FSI pixels. At that size, FSI pixels impose requirements upon certain camera components, such as a larger lens.

Other advantages OmniBSI offers include a higher sensitivity per unit area, improved quantum efficiency, lower pixel crosstalk, and photo response nonuniformity. Also, BSI supports a larger aperture size, which allows for lower camera-lens f stops. For more details, visit www.ovt.com.

WHITE LED SCALES THE BRIGHTNESS LADDER
Exactly how much brightness can be squeezed out of one white LED? We may never know because when higher brightness is necessary, Osram Opto Semiconductors designs a new and brighter LED.

Back in July 2008, the company set what it calls a world record for brightness and efficacy with a white-LED prototype using 1-mm² chips. The component is capable of 155-lm peak brightness and 136-lm/W efficacy (Fig. 2).

The prototype delivers this performance under standard operating conditions using a forward current of 350 mA. Furthermore, with color coordinates at 0.349 (CX) and 0.393 (CY), the component produces a color temperature of 5000 K.

Timely advances in materials and LED technologies, Osram claims, are responsible for creating this matched combination of parts consisting of optimized chip technology, an efficient light converter, and a high-performance package. The prototype also supports higher operating currents. At a drive current of 1.4 A, it delivers up to 500 lm of white light (Fig. 2, again).

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GUARANTEED BANDWIDTH
At least a half-dozen companies make transceivers for the 802.11n Wi-Fi standard. All comply with the Draft 2.0 standard and the Wi-Fi Alliance’s interoperability guidelines so they can deliver at least 100 Mbits/s within the typical unobstructed 100-m range. They also interoperate but lack any significant distinction from one another. Yet Quantenna Communications’ QHS Wi-Fi chips change that tune with significant features and improvement over the more common chips.

When dealing with limited multipleinput multiple-output (MIMO) of the 2-by-2 or 2-by-3 variety, link distances and throughput rates are typically unpredictable. Thanks to an unending number of environmental conditions, you can only guess your connection range and speed.

Limited range means that coverage in a home or with an enterprise access point will have dead zones, ultimately translating into connection unreliability. In critical applications like video, that can greatly limit the usefulness of wireless. In fact, few vendors will support video over Wi-Fi.

Product size or printed-circuit-board (PCB) footprint can also be an issue in packaging. To achieve longer range, higher speeds, and reliability, typically more chips must be used, which increases product size. Finally, power consumption is always at the forefront of most new designs.

The QHS series removes many of these limitations. The family offers raw data speeds up to 1 Gbit/s with a throughput up to 600 Mbits/s. Range and reliability get a boost from a 4-by-4 MIMO scheme as well as transmit beamforming. These features alone account for a 10- to 11-dB advantage over the closest competitors.

Range and reliability are also extended by the availability of a vector mesh networking capability with spectrum management. Mesh node routing easily expands coverage depending on the number of nodes used. Whole-home coverage becomes almost automatic with the Quantenna solution.

The QHS series is highly integrated, which means fewer chips and discrete components are needed, saving lots of PCB space. Bill-of-materials (BOM) costs are also lower than competitive solutions.

The top-of-the-line series member, the QHS1000, is a fully integrated chip set that delivers 1 Gbit/s (Fig. 2). It comes in either a dual 4-by-4 or quad 2-by-2 MIMO configuration and operates on both the 2.4- and 5-GHz unlicensed spectrum.

In the chip set, the QHS600 delivers up to 600 Mbits/s in either dual 4-by-4 or quad 2-by-2 form and operates only in the 5-GHz band. It targets video applications. The QHS450 offers up to 450 Mbits/s and comes in a single 4-by-4 or dual 2-by-2 configuration. Designed for data-intensive uses, it operates in the 2.4-GHz band.

Quantenna offers its own OS to help designers implement a fully featured access point. Vendor-specific applications are easy to port to the OS. The QHS chip sets are sampling now. Contact the company for pricing.

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