Chip design allows high performance with low power consumption

Two decades ago, in a world where chipsets were largely manufactured by a handful of monopolies, semiconductor company ARM Holdings stormed the silicon world with its remarkably power-efficient chipset designs. Today, ARM processors power over 95 per cent of mobile devices worldwide.

With the release of Windows RT, an operating system that supports ARM-based processors, the British-headquartered company is now challenging Intel Inc. in its traditional stronghold, the PC chipset segment, and has its eye on the server hardware market. ARM itself doesn’t manufacture chipsets; it licenses intellectual property on processor technology and systems-on-chip designs to companies such as Samsung, Apple, Qualcomm and Nvidia.

All these years, and hundreds of chipsets later, ARM’s focus on power efficiency of chipsets remains unchanged. A crucial area of innovation, given that taming power-hungry applications is today a primary gadget challenge, ARM’s new systems on chip architecture promise a fix that is as basic as it is complex.

It’s basic because the idea is simple: create a hybrid that toggles between hardware, according to what the system requires, similar to a hybrid car, and it is complex because shifting between processors or processor cores is by no means easy given the small and intricate circuitry involved.

This is why ARM’s big.LITTLE is nothing short of remarkable. Its systems tweak allows high performance with low power consumption, something that gadget manufacturers hope will increase battery life by as much as two-thirds.

How does it work?

So how does big.LITTLE work? The basic idea is to pair two processor cores (or clusters) — one tiny and low-power one with a large superscalar core — and allow the system’s software to seamlessly and dynamically switch between the two, depending on energy requirements. For instance, a big ARM Cortex-A15 processor is paired with a LITTLE Cortex-A7 processor, and both are architecturally compatible. This combination, ARM reports, has improved battery life by 70 per cent.

Is most of this still on the drawing board? The answer is no. ARM claims that over 15 original equipment manufacturers have already licensed the technology.

In fact, last month, South Korean electronics major Samsung announced its 8-processor core chipsets based on this big.LITTLE tech architecture, which the company confirms lowers power consumption by as much as 70 per cent. Japanese semiconductor manufacturer Renesas Electronics is next in line, says Graham Budd, Chief Operating Officer, ARM Holdings.

Speaking to The Hindu on the sidelines of the IESA Vision Summit 2013, Mr. Budd said that this multicore approach to match processor and processor speed to the processing task at hand is what will be a “real game-changer” in the chipset space. It’s the same concept as a hybrid car, he explains, where batteries power operation during, say city travel, but the engine switches to fuel once the car hits the highway.

Primary challenge

What is the primary technological challenge to making the system toggle between different cores or processors? “The technological challenge in implementing this complex multicore architecture lies in being able to switch seamlessly between two different-sized processors. The innovation lies in a combination of hardware and software that makes it possible for the system to learn and understand what app you’re opening, and how much power that’s going to require, or predict where you’re likely to go next on your device,” Mr. Budd explained.

Though he maintains that big.LITTLE is the most exciting and cutting-edge innovation in silicon today, Mr. Budd predicts that ARM’s low-power architecture will power everything from small smartwatches that can run your gadgets in the ‘Internet of things’ to large server rooms.

He pointed out that though ARM is focussed on mobile devices, a market that he knows is where the “explosive growth” lay, he pointed out that sectors such as smart grids, servers and networks are going to be big.

In 2012, out of the 8.7 billion ARM processor chips that were shipped, around 50 per cent went into mobile devices. But, an equal number of chips powered digital TVs, microcontrollers, networking interfaces, in-vehicle entertainment and so on, he pointed out.

‘The real DNA’

Whatever the type of gadget, he pointed out, the “real DNA” of the chips lies in the energy-efficiency quotient. “And this requirement is constant. Whether it’s a smartwatch or a backend server, the primary requirement is energy efficiency. We’ve been leaders in low-power design and that’s where we continue to focus. The more complex interfaces get, take for instance augmented reality, the more power it is going to use. Device hardware needs to constantly innovate to meet this challenge.”