Friday, September 14, 2012

What's Under the Hood

Folks who know me know I love to look under the hood. I want to know what’s powering that thing, whether it is an LS9 engine from a top model of Corvette or the microprocessor running the latest electronic gear. In both the case of automobile engines and computer processors, the beauty is in the balance between performance and weight / size / economy.

Modern mobile devices such as smartphones demand a compromise between battery  life, performance, heat, power, and cost. So when Apple launched its latest iPhone, I immediately asked, “What’s under the hood?” In some cases, Apple isn’t talking. They simply identify the new processor as the A6 -- successor to the iPhone 4s installed A5.

We know this new processor is more powerful, yet Apple is claiming better battery life ... even with the power hungry 4G LTE technology added to the "swiss army knife" Qualcomm communications chip able to talk all sorts of technical languages in world-wide settings. Although this single chip provides support for all the US cell phone carrier's technology, 2G, 3G, and 4G, plus technologies used overseas, putting all that in a single chip increases battery drain.

A little research found the analysts at Nomura Equity Research opinion that the A6 processor inside Apple's iPhone 5 is a dual-core Cortex-A15 manufactured for Apple by Samsung Electronics Co. Ltd. in its 32-nm HKMG (High-K Metal Gate) manufacturing process.

(The term high-K dielectric refers to a material with a high dielectric constant, “κ,” as compared to silicon dioxide used in most semiconductor manufacturing processes. The high-κ metal gate replaces the silicon dioxide gate dielectric. The implementation of high-κ metal gate is one of several strategies developed to allow further miniaturization of microelectronic components. See:

This would mean Apple is one of the first companies to introduce a Cortex-A15-based processor. Cortex-A15 is the highest performance processor core from intellectual property licensor ARM Holdings.

Samsung started sampling the industry's first dual-core ARM Cortex-A15 processor late in 2011, the Exynos 5250, made with its 32-nm HKMG process and intended for volume shipment in summer 2012. Its 2-GHz clock frequency is claimed to double the performance of the previous 1.5-GHz dual-core Cortex-A9 based Exynos, which fits with Apple’s performance claims for the new phone.

It is not surprising that Apple has turned to Samsung, the competitor that it has sued for copyright infringement in their own smartphones. At IBM we were well aware of the modern technical culture where a company is your competitor on one hand, and business partner on the other. After all, IBM had the world’s largest Windows consulting service at the same time we were strongly pushing Linux as the best office OS solution. Never mind “if you can’t beat them, join them.” Our strategy was to do both. I suspect Apple is doing the same.

The A6 is a very interesting design and is part of the movement from 32-nm processor design to the ultra-small 22-nm process. IBM partner GlobalFoundries, current source for both 32-nm and 28-nm processes, demonstrated its first 22nm equivalent oxide thickness (EOT) in a high-k metal gate (HKMG) transistor capable of scaling down to the 22-nm node while maintaining low leakage, low voltages, and superior charge carrier mobility. Such technology will enable continued VLSI semiconductor scaling to the 22-nm process, and likely beyond.

The triumph here comes from maintaining the transistor’s precision when the EOT in a high-k oxide layer is reduced sufficiently for 22nm features. If reduced too much, it results in an increased leakage current, which robs the 22-nm node of any power saving benefits.

GlobalFoundries and IBM were able to overcome this limitation by maintaining an appropriate EOT at the level necessary for 22-nm and beyond, one which maintains the necessary combination of leakage, threshold voltages, and carrier mobility.

On the other hand, although Apple choses the very highest technology for the processor design, they continue to use hand assembly. The design of the iPhone is enhanced by stacking components in what is called a 3-D architecture and using ten-layer printed circuit boards with drilled vias to reduce size.

These extremely compact designs require hand assembly since they are beyond the capability to be assembled by machines. The competition’s smartphones will continue to be a little thicker, a little larger, and often with smaller batteries because they are designed to allow easy assembly by machines. The iPhone, on the other hand, uses small screws and manual assembly techniques that make them more like fine watches than computers produced by robots. This more expensive assembly is possible with Apple’s premium price structure, while allowing Apple to produce the thinest and lightest mobile devices around.

If Samsung is the sole supplier of the A6 processor – as indicated by Nomura analysts – this squares with recent predictions that Taiwan Semiconductor Manufacturing Corporation, the world's largest dedicated independent semiconductor foundry, is working on pulling in its 20-nm process and working to supply Apple in the second-half of 2013 using that process.This comes shortly after TSMC denied both Apple and Qualcomm’s bids to become equity partners and provide exclusive access to these advanced designs. So the technology is there for anyone who can incorporate them in their products. So far Apple maintains a lead over its competitors in this regard; even the competitor which it uses to source the high technology parts.

This new phone comes out at a time when I’m upgrading the disk drives in my home system. I’m replacing all my 500 giga-byte drives with the four-times larger, 2 tera-byte storage. There continues to be no end in sight, either with the small scale of processor design, nor the large size of disk drives. At this rate, semiconductors will be designed using only one atom per gate, while disk storage will hit femto-bytes. Is it any wonder I get excited looking under the hood.

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