Embedded cores
Posted:29 Jun 2009
Teardowns of the third generation Apple iPhone reveal a more integrated—and probably lower cost—handset thanks in part to new design wins for Broadcom and Toshiba. That's caused one analyst to quip the 'S' in the iPhone 3GS may stand for savings.
Elpida also made its first entry into the iPhone with the 3GS, with DRAM die appearing in two chip stacks. Elpida and Toshiba have supplanted Samsung as a supplier of flash and DRAM in the handset.
The iPhone 3GS arrived at Apple retail stories June 19 to lighter than previous sales.
"The biggest surprise in the iPhone 3GS is there are no Marvell Wi-Fi or CSR Bluetooth chips" that appeared in earlier iPhones, said Young Choi, senior manager of engineering at Semiconductor Insights who is doing a teardown of both the handset and major chips in it.
Apple opted for a Broadcom BCM4325 integrated 802.11abg and Bluetooth part already used in the iPod Touch, likely saving space and cost. The iPod Touch "now appears to be a leading springboard for new suppliers and integration in subsequent iPhone generations," said David Carey, president of teardown specialist Portelligent (Austin).
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Analysts are still cranking the numbers on Apple's costs of producing the iPhone 3GS. "It's lower than the first-generation iPhone 3G," due to reuse of many existing components and declines in memory prices, said Carey.
Toshiba helped Apple squeeze more storage in a tight space by delivering a 16 GB NAND flash device that stacks four 32 Gbit die in a single package. The 32 GB version of the phone is expected to pack eight of the dice in a similar package.
Choi said the Toshiba part was the first four-level stack of a 32 Gbit flash die he has seen to date. Intel and Micron released some of the first 32 Gbit parts in January using a 34 nm process. The 210-square mm Toshiba die was probably made in the company's 43nm process using its existing all-bit-line architecture announced about 18 months ago.
An Intel/Numonyx device new to the iPhone provides memory for the base band processor. Choi said he believes it includes a 16 MB NOR die and a 512 Mbit Elpida DRAM die, although he has yet to conduct detailed chip-level analysis on the part.
One of the biggest mysteries of the 3GS is the applications processor widely expected to be an upgraded version of the 90nm Samsung part in the first two generations of the iPhone. As with the earlier designs, the package markings on the chip do not correlate directly to anything in the Samsung product portfolio.
The package bears both Apple and ARM logos along with numbering suggesting a Samsung memory multi-chip package, Choi said. He plans to conduct a detailed cross-section analysis of the chip, measuring transistor sizes and other key metrics.
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Many observers speculated the part includes a 600 MHz ARM Cortex A8 and PowerVR SGX graphics core from Imagination Technologies in an SoC made in a 65nm process. Such a chip would be on par with the OMAP 3430 from Texas Instruments used in the Palm Pre.
"That's based on speculation and press releases," said Choi. "We haven't yet identified any functional blocks to determine what [the Samsung part] actually is," he added.
Indeed, even the markings on the die of the applications processor (pictured below) do not describe the heritage of the part.
It's also possible the design is a custom ASIC built for Apple. The company has been working for more than a year to build up a strong internal semiconductor team to define proprietary silicon for its systems.
Carey said the apps processor includes two 128 MB Elpida Mobile DDR SDRAMs in a stacked package-on-package. That gives the 3Gs processor 256 MB of working memory, and another design win for Elpida in the high profile handset market. Elpida mobile SDRAM was also found in the Palm Pre.
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"The use of a new Samsung apps processor and an Omnivision auto-focus 3 Megapixel camera certainly bumps the costs up, but these improvements along with a few incremental bells and whistles would seem to be offset by declines elsewhere in the system," said Carey.
Another surprise is the new handset apparently still uses the Infineon PMB8878 also known as the XGold 608 base band processor in previous designs, according to Carey of Portelligent. Apple doubled to 7.2Mbpsecond the download speed supported on the iPhone 3GS, but that speed grade was apparently already supported on what is clearly the old Infineon chip based on die markings.
Some other findings from Portelligent included: the 3-axis compass chip (used in the new GPS feature of the phone) being manufactured by AKM Semiconductor, the audio codec coming from Cirrus Logic, and Dialogue Semiconductor providing the power management unit for the application processor.
Infineon again found themselves a major IC design-in benefactor in the iPhone 3Gs; with their base band processor, power management chip (the SMARTi Power 3i), and their UMTS transceiver (used in the original iPhone 3G) all finding themselves in this new iPhone.
- Rick Merritt
EE Times
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