Evolution of Resolution

By Suzanne Deffree -- Electronic News, 3/18/2005

Analog Devices Inc. (ADI) wants to make camera phone users smile.

The company this week announced an integrated lens driver for cell phone cameras with an auto focus feature. The first in a new analog portfolio for ADI, dubbed AD5398, takes aim at camera phones that have hit and are exceeding the 1 megapixel point – a resolution that ADI said lacks clarity in camera phones.

"One of the major barriers to camera phones is auto focus," Mel Conway, product marketing manager at ADI, said. "As the resolution of your camera phone is increasing, the clarity of the image is not increasing -- and it's not increasing because most camera phones lack auto focus."

Notes Conway, camera phones have become more and more popular based on their convenience factor and resolutions continue to evolve, climbing to 2 megapixels with Toshiba's announcement this month.

"The key thing about a camera phone is connectivity and immediacy. Most people almost always have it on their person. The problem so far has been the resolution has been so poor, it's only been a novelty. As it improves, due to lower costs, then the resolution is coming close to and converging with still camera performance," he said.

ADI's lens driver move targets the future of camera phones -- ones Conway believes will challenge digital still cameras -- offering an all-in-one solution that pushes auto focus to consumers, which should put the company ahead of the game, according to Databeans Inc.

"If you look at the future and also the different uses for auto focus, consumers will really demand that kind of a feature on phones because they will discover all kinds of new uses for these devices," Myson Robles-Bruce, a research analyst at the firm, said. "It's going to go well beyond the typical camera phone today.

"[The chip is] a case of ADI really jumping ahead of other competitors with this," added Robles-Bruce. "Typically, other lens drivers include only motors, but this is an all-in-one solution."

The lens driver includes a fully integrated and optimized lens motor and actuator driver design that is one-fourth the size and one-half the cost of existing discrete solutions, according to ADI. AD5398 features 120-mA output current sink capability and 10-bit resolution, exceeding the typical performance requirements of the application, ADI reported. In addition to a 10-bit DAC, included on chip are a current sensing resistor, inductive protection diodes and an internal reference.

"Digital cameras have been around for 10 or more years. They drive their lens using lens drivers, of course, but they were always just power transistors, dumb and powerful -- and that meant large and cheap," Conway said. "What we are bringing to market here provides very different functions … such as power management, boost converters or charge pumps, voltage registers, controls for your shutter and all your stuff in a camera device."

The inclusive analog device is also suited for digital still cameras, digital video cameras, and the like. But ADI is focusing on the camera phone market because, as Conway said, "a 36 percent growth rate and 650 million units is nothing to be sneezed at– and business is only taking off in camera phones. It's not like digital still cameras where it's fully mature."

Overall, ADI estimates digital still cameras are going to reach 120 million units in 2008. "If you add in all the other types of cameras, you're talking about approximately 1 billion camera devices in 2008," the manager estimated. "All of these or many of them will require lens drivers of some description."

ADI said it is working with top cell phone players now for products based on AD5398. The company has plans for a second-generation lens driver solution in the summer timeframe.