iPhone 5 A6 chip may perform better than expected due to manual layout – yes, logic blocks laid by hand, not software

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image thumb1241Benchmark tests of the iPhone 5 against powerhouse devices such as the Samsung Galaxy S3, are showing that the A6 chip is indeed a very capable processor. In most test scenarios the iPhone 5 outperformed the Galaxy S3 and in some cases even outperformed the iPad. Now the guys at Chipworks may have discovered the reason for its blazing speed. The chip is a custom Apple creation based on the ARMv7s instruction set, and manufactured by Samsung. During a teardown performed by Chipworks (and confirmed by iFixIt), they found that the ARM core blocks appear to have been laid out manually – as in, by hand. If so, this would be the first manually laid-out chip to hit the market in several years. Laying out the core design by hand is expensive and time consuming but results in optimized high-frequency operation of the chipset.

Engineers at Chipworks used ion beam etching to remove the casing material from the A6 and then examined the chip under a microscope. They found that the detailed layout of the ARM cores isn’t typical of integrated circuits that are laid out using software, the common approach to chipset design.

“When compared to the rigid, efficient layout of the GPU cores directly below it, the layout of the ARM cores looks a little homespun—at first. Generally, logic blocks are automagically laid out with the use of advanced computer software. However, it looks like the ARM core blocks were laid out manually—as in, by hand. A manual layout will usually result in faster processing speeds, but it is much more expensive and time consuming.”

The photos below, courtesy of Chipworks, show the difference in a normal computer-generated core design and the Apple A6 core.

Normal ARM core

Normal ARM core


Apple A6 Hand laid core

Apple A6 Hand laid core

Sources: Chipworks, iFixIt


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