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Rich features define cost-conscious phone

Posted: 10 Jan 2008 ?? ?Print Version ?Bookmark and Share

Keywords:Tianyu B811 teardown? low-cost phone? flash memory?

At an estimated total cost to manufacture of less than $45 based on a Portelligent teardown analysis, the Tianyu B811 finds itself positioned just above the ultralow-cost voice-only phones, where BOM costs have now dropped below $30. The incremental difference of $15, although not small in this competitive, margin-thin segment of the cellphone market, results in a much more capable handset than those found at the bottom of the market. Color display, VGA camera, GPRS data connectivity, MP3 playback capability and 64Mbytes of user storage equip the B811 with features once reserved for only the highest-tier phones.

To fit these features into a phone with an estimated cost to manufacture of just below $45, Tianyu relied on technologies found in top-shelf 2003 to 2004 handsets. The technologies have dropped in cost to the point where they can be profitably added to low-end cellphones.

Reinventing low-cost design
The display found in the Tianyu phone is a 1.5-inch-diagonal, 65,536-color STN model with a resolution of just 128 rows by 128 columns. The size, technology and resolution of the display are more indicative of the primary displays found in 2003 midrange to high-end cellphones and the secondary displays in today's high-and ultrahigh-end cellphones.

With a pixel density of 115, the Tianyu B811 display falls in the bottom third of primary phone displays analyzed by Portelligent over the past four years. The positive tradeoff of using a mature technology and low-resolution display is the cost: The B811 has one of the lowest-cost primary color panels analyzed by Portelligent.

Similarly, the B811's camera, with an OmniVision OV7660 VGA CMOS image sensor, is equivalent to the camera capabilities found in three- to four-year-old high- and ultrahigh-end phones such as the Nokia 7650. The Tianyu B811 camera module, manufactured by Sunny Innovation in China, is little more than a plastic housing, a couple of plastic lenses and a PCB with the image sensor mounted to it. By using a design not too different from the camera module found in the Nokia 7650, Tianyu reaped cost savings that let it place a camera in the B811. The savings come from wringing cost out of the five-year-old design and from semiconductor process improvements that have reduced the size of the image sensor by more than 40 percent.

Tianyu B811

The Tianyu B811 finds itself positioned just above the ultralow-cost voice-only phones.
(Click to view teardown.)

Lacking the imaging chain in the digital baseband required to process pictures from the VGA sensor, the Tianyu B811 requires a separate PixArt PAP1302 multimedia processor to handle all image manipulation. Discrete imaging processors have been showing up in Portelligent teardowns of camera phones since 2002, but the PixArt processor, at just over 10 mm? and only capable of processing VGA-resolution images, is one of the least expensive.

Data capability
Dual-band (900/1,800MHz) GSM/GPRS data capability is provided by a MediaTek MT6218 digital baseband processor stacked with an analog baseband in a package configuration common to many phones analyzed by Portelligent. Despite the diminutive die area (39mm?), the MT6218 provides enough horsepower to enable MP3 playback, which is pumped through a 1W audio amplifier from On Semiconductor to the wired stereo headset.

The communication software and application software for the digital baseband are stored in a Spansion multichip package containing 8Mbytes of NOR flash memory and 2Mbytes of ETron low-power pseudo-SRAM. The other key cellular components are a MediaTek MT6129 GSM transceiver, an RF Micro Devices RF3166 power amplifier module with two power amplifiers and a PA controller, and a MediaTek MT6305 power management IC. The RFMD PA module first appeared in 2005 in high-end, UMTS handsets amplifying the GSM/GPRS portion of the radio. More recently, it has been seen in low-end GSM/GPRS-only cellular phones, such as the B811.

Without an external card slot, the multimedia capabilities of the B811 required Tianyu to provide an ample amount of user storage for music and photo files. Unique for a phone in this low-end segment, a generous 64Mbytes of memory is provided by a single-die, NAND flash memory package from STMicroelectronics.

'Minimalist approach'
The remainder of the B811's cost resides in the mechanicals and battery. Both indicate a minimalist approach that enabled Tianyu to afford the multimedia capabilities designed into the phone.

The candy bar shape of the handset is generally the least expensive form factor, eschewing expensive sliding/pivoting mechanisms, wiring harnesses and dual displays. The low-cost battery found in the phone has a miserly 600mAh of capacity in a Li-ion battery pack with one of the lowest cell energy densities observed by Portelligent.

Through the use of proven, mature technologiesalong with a few cutsTianyu has shown that features once reserved for high-end handsets just a few years ago can be designed into today's low-cost phones. With competition and innovation continuing unabated in the cell phone market, look for the QVGA resolution, TFT displays, megapixel cameras and high-speed data connectivity found in today's high-end phones to find their way into tomorrow's low-end handsets.

- Jeff Brown
Principal Analyst, Portelligent

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