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iPhone 3G still packs some surprises

Posted: 15 Jul 2008 ?? ?Print Version ?Bookmark and Share

Keywords:iPhone 3G? GPS? design win? teardown?

Aside from some very surprising component choices in key parts of the upgraded communications section, as well as some software improvements and some basic design tweaks, the old adage 'if it ain't broke, don't fix it' has clearly shaped the design of Apple Inc.'s iPhone 3G.

"It's incrementalism at play," said David Carey, president of teardown specialist Portelligent. "They learned a bit from their 'Touch' solution and replaced two boards with one."

Instead of trying to reinvent the device, Apple focused on enhancing the user experience and expanding its fan base. It has done this by not only expanding its geographical footprint and speeding up its wireless connection, but also through the iPhone applications development network. Clearly one of the bigger stories behind the 3G launch, the developer program will see Apple providing resources, real-time testing and distribution, to accelerate the delivery of more diverse applications to the consumer.

The success of that program will be determined over the coming months, but for those consumers with an iPhone 3G in hand, there will be little to 'oooh' and 'aaah' about, aside from the 3G data rates, where available.

Surprise design wins
From the outside, the phone looks very much the same, except for a plastic backing and a move away from a recessed headphone jack to a flush connector. It has the same look and feel and the same 2Mpixel camera feature. That said, it does add built-in GPS capability and MobileME application software.

Analysts from Portelligent, as well as TechOnline and Semiconductor Insights, were taken aback by the strength of Infineon's wins in the 3G communications portion, as well as the inclusion of TriQuint for three front-end modules.

"Infineon clearly made their mark on this board with four key design wins," said Allan Yogasingam, a TechOnline technology analyst. "And TriQuint really came from left field with their win their modules. I didn't see a single press-release or speculative article hinting at a relationship between the two companies. In today's internet world, that's a tough thing to keep under wraps."

TriQuint provides three power-amplifier (PA) front-end modules, the first is the TQM676021, which is an integrated 3V linear UMTS Band 1 PA, duplexer and transmit filter module, with output power detector. It supports high-speed uplink packet access (HSUPA) operation with transmission data-rates up to 10Mbit/s. Next is the TQM666022, a similar device, but for Band 2 operation. Finally comes the TQM616035 W-CDMA/HSUPA PA-duplexer module for Band 5 and 6.

Moving up the signal chain, Infineon won big. It supplies the UMTS transceiver, suspected to be the PMB 6952, as well as the baseband processor, which is actually a two-chip module in a single package. The first chip is the X-Gold 208 (PMB 8877), which caters to GSM/GPRS/Edge waveforms. The second chip is marked the PMB 8802 and is suspected to be the W-CDMA/HSDPA accelerator for 3G. While there's still some debate as to whether this combo package with Apple markings may in fact be Infineon's XGold 608 (PMB 8878), which TechOnline product manager Greg Quirk Quirk and analyst Allan Yogasingam expected to see, that chip has as yet not become available to verify under Semiconductor Insights' microscope.

"In any case, that it's broken into two chips is surprising," said Carey, given that both Nokia and Qualcomm have integrated both functions it into a monolithic die. However, there may be more to the decision than design choice. "We suspect the second die has something to do with one of the InterDigital patents," said Yogasingam, referring to an Apple, InterDigital patent dispute last year.

The baseband's support memory comes courtesy of Numonyx, the Intel/STMicroelectronics spin-off. It includes 16Mbyte NOR flash and 8Mbyte pseudo-SRAM (PF38F3050M0Y0CE).

Rounding out the communications function is the Skyworks SKY77340 824- to 915MHz quad-band GSM/Edge amplifier module, the same part used in the original iPhone.

Click to view larger image

Power management in the iPhone 3G is split between two ICs: the communications portion of the device is handled by Infineon's SMARTi Power 3i, while system-level power control and management is handled by NXP (exact device to be determined, though Carey believes it's the #PCF50633, as per the original iPhone.)

The Linear Technology LTC4088-2 takes care of battery charging and general USB power control.

Built-in GPS
Aside from 3G capability, one of the big differentiators of the new iPhone device is its built-in GPS capability, which is provided by yet another Infineon chip, this time the PMB 2525 Hammerhead II. "In the old one [original iPhone], GPS was software enabled and was accurate to within blocks," said Quirk. "This time it's accurate to within meters."

The Hammerhead II integrates an assisted-GPS (A-GPS) baseband processor with a low-noise GPS RF front end and multi-path mitigation to avoid large errors in urban environments. While the die markings indicate it's actually a PMB 2520 Hammerhead I chip, Quirk pointed out that it's common practice take the same die, make some fairly simplistic connection or routing changes to alter or improve functionality, and then re-label it as a 'new' chip.

Click to view larger image

Memory support
For the main applications processor, Apple chose to stick with a tried-and-true Samsung ARM11-based design, with some tweaks, supported by 128Mbyte stacked, package-on package, DDR SDRAM, also from Samsung. Externally, the main memory comes in two versions for the iPhone: 8Gbyte and 16Gbyte NAND flash. In this case, it is 8Gbyte, but the source was surprising: Toshiba, in the form of a single-chip device segmented into four, 2Gbyte die (TH58NVG6D1D).

According to Quirk, the choice of Toshiba was unusual given that Apple had a "huge" deal to buy all Samsung memory. It also was reportedly discussing plans for volume purchase of NAND flash chips that will be used in all iPods and iPhones from June to December 2007 (Source: EE Times-Asia.)

"To see Toshiba makes me wonder if that deal is no longer in place," he said. Granted, those deals are aging, he acknowledged, "but now that the new iPhones have come out and seem to be using Toshiba, does this mean that Samsung is playing second string to Toshiba? It could mean some good stock boost for Toshiba!"

With regard to the current 16Gbyte maximum offered with the iPhone 3G, Quirk suspects that may not be enough, given that half a gigabyte can disappear for just one compressed movie. Add photos and MP3 files and Quirk sees that 16 Gbytes getting eaten up pretty fast.

The SST25VF080B 8Mbit serial flash chip from SST rounds out the iPhone 3G's memory support.

The tried-and-true philosophy symbolic of the new iPhone extends to the accelerometer, the LIS331 DL from ST, as well as the single-chip 88W8686 single-chip Wi-Fi offering from Marvell. The Marvell chip is accompanied on the back of the main board by a CSR BlueCore6-ROM Bluetooth chip, which surprised the analysts, all of whom were expecting to see the same BlueCore4 device used in the original iPhone.

Rounding out the main chips on the iPhone are the Wolfson WM6180C audio codec, which replaces the WM8758 used on the original iPhone, as well as the Broadcom BCM5974 touchscreen controller, National Semiconductor LM2512AA Mobile Pixel Link display interface and the Texas Instruments #CD3239 touchscreen line driver.

The new iPhone's touchscreen approach is the same as that of the iPod Touch, said Carey. The Gen1 iPhone had three chips for the touch screen solution: a Broadcom controller, a NXP 32bit uP, and a TI line driver. The Touch reduced this to just a revised Broadcom chip (which absorbed the microprocessor function) and the TI line driver. "The 3G uses the same Broadcom chip as the Touch, and an updated TI line driver (smaller chip)."

While Apple's rollout of the iPhone 3G may not have been met with the same frenzied reception as the original, its fan base remains strong, according to Yogasingam. "After spending the better part of the night with people waiting in line for an iPhone, I'm still amazed at how many people have embraced the Apple brand and are willing to do anything to be an early adopter of anything hip and new from Apple. Apple has this air with its fan base that it could do no wrong."

- Patrick Mannion

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