iPhone 4拆解心得：苹果的“复用”精神

Updated: First look insideiPhone 4reveals high reuse

by Rick Merritt

You could call the new Apple iPhone 4 an iPad Nano because it uses at least seven chips from the popular Apple tablet, according to analysts from UBM TechInsights that have done a teardown of the new smartphone. STMicroelectronics won a coveted design win for its MEMS gyro in the handset.

The teardown specialist is preparing a full report on the iPhone 4. UBM TechInsights is a division of United Business Media, the publisher of EE Times.

Like the iPad, iPhone 4 uses Apple's A4 as its applications processor. However it uses a version with twice the memory—512 Mbytes of Samsung Mobile DDR SDRAM. Specifically the part uses the Samsung K4X4G643GB, a package-on-package stack of two 2 Gbit die.

Design reuse is clearly a big focus for Apple these days. For example, the iPhone 4 continues Apple's use of baseband and transceiver chips from Infineon despite a highly competitive market for such chips. The handset also uses the same Dialog power management chip Apple put in the iPad.

The iPhone 4 also reuses several other iPad parts including a Broadcom Bluetooth FM radio combo chip (the BCM4329), Broadcom GPS device (the BCM4750) and Cirrus Logic audio codec (the 338S0589). The iPad and iPhone 4 also share in common two memory chips—a Samsung 256 Gbit NAND flash device (the K9TFG08U5M) and a combo device from Numonyx.

"If you are a supply chain guy negotiating for lowest price, you know these chips have millions of iPad sockets and now millions more for the iPhone 4," said Steve Bitton, a senior analyst with UBM TechInsights working on the iPhone 4 teardown.

MEMS gyro and cameras

At the launch of the iPhone 4 in June, Apple confirmed it was one of the first smartphones to use a MEMS gyro.

The iPhone 4 is the first to use the ST Micro L3G4200D three-axis MEMS gyro. UBM TechInsights confirmed the gyro is an ST part based on die markings. It offers digital output which eliminates the need for conversion circuits needed for devices that output analog signals.

"Going with the ST device makes a lot of sense since they also use an ST three-axis accelerometer," said Bitton.

The iPhone 4 uses the LIS331DH 3-axis accelerometer, another part in common with the iPad.

Apple is driving a new CoreMotion API based on the use of the gyro, accelerometer and a digital compass. It will be interesting to see whether application developers make use of the gyro which is only available on the iPhone 4, forcing them to create different versions of their code for other Apple products, he added.

"I expect a gyroscope enabled iPad in the near future," said Bitton. "Looking at the iPad PCB, there is space for a 4mm x 4mm device right next to the accelerometer—that's the size of the ST L3G4200D," he said.

The phone's front-facing five-Mpixel camera is most likely the Omnivision OV5650 based on specifications and preliminary die photos inspection. It is a relatively modern choice compared to image sensors in past iPhones, and it supports Omnivision's backside illumination technology.

"Typically Apple uses older image sensors to save a few dollars," said Bitton.

The front-facing image sensor is also from Omnivision, the OV7675 a VGA-resolution device.

The use of three Skyworks analog front-end communications modules in the iPhone 4 is more true to Apple's penchant for older, less integrated parts. The three modules support separate GSM/GPRS, WCDMA and Euro-Asia band cellular radios.

UBM TechInsights published initial results of its teardown on its Web site. It wrote an initial analysis of the A4 processor earlier this year. The group also confirmed in May the chip contains an ARM Cortex A8 core designed and fabricated by Samsung.

Also in May they estimated the iPhone 4 would have bill of materials cost of as much as $170.

Apple published a basic list of the iPhone 4's tech specs online.