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Complexity could see power management chips becoming the next integration platform within mobile phones

Bagherli: "We are dependent upon process technology."

Having long been one of the least heralded parts of an electronics design, the power supply is now one of the most important components. And, according to Jalal Bagherli, pictured, chief executive of Dialog Semiconductor, power chips are likely to provide the basis for the second integration centre in a mobile phone.
Addressing the Global Semiconductor Alliance's recent executive forum, Bagherli said the way in which the mobile phone was developing was creating problems. "Users want to access apps frequently and they want their devices to be always on. On top of this, there are bursts of activity."

While mobile phone developers attempt to meet these needs through integration of different radios, there are consequences when it comes to power. "They need to choose the most effective wireless interface for each application," he claimed. "There can be up to eight radios in a smartphone, each of which has different latencies and bandwidth requirements."
In particular, he said the move towards multicore ARM based applications processors was driving demand for more complex power management ics (pmics). "Each ARM core may have four different power modes and, when the four cores in a quad core device work flat out, this requires a high peak current."
The problem was easier to deal with in earlier phones, he admitted. "In 2G, we could integrate the pmic into the application processor using a 90nm process. At 3G, the baseband and apps processor pmics were integrated, but on a separate 0.25µm chip. For 4G, there will be the need for external baseband and apps processor pmics." Dialog expects these to be made on a 130nm process using 300mm wafers.
Higher levels of functionality have led Dialog to integrate ARM cores into its pmics so users can program the devices to meet the specific needs of their products. "This means we need a close relationship with our suppliers," Bagherli said, "because we are dependent upon process technology."
Dialog and TSMC have jointly developed a next generation bipolar cmos-dmos (bcd) technology tailored specifically to high performance pmics. According to Dialog, the bcd process can support the integration of advanced logic, analogue and high voltage features, allowing it to create the more integrated devices Bagherli outlined.
He said Dialog also relied on its packaging suppliers "We are being driven by apps that didn't exist before," he noted. As complexity grows, so too is chip size. Bagherli said a pmic in 2007 required 10mm2 of silicon. "In 2012, pmics need 40mm2. That requires more complex packaging and we are stacking chips in package to integrate other functions."
He said pmics were already shipping that stacked audio devices. "Other functionality might include fuel gauging and a connectivity hub; for example, managing the wireless lan," he concluded.
Meanwhile, in another address to GSA delegates, Rene Penning de Vries, NXP's chief technology officer, claimed only 40% of energy supplied in the US was being consumed effectively. He said there were four main areas where semiconductors could help to improve power efficiency: energy sources, distribution and storage; power conversion; power management; and smart grid/smart buildings, as well as battery management.
"There are around 3billion chargers produced a year, half of which are supplied with mobile phones. "We can afford to include more intelligent silicon in these chargers and 3bn times a small improvement will bring big savings," he claimed.
He also pointed out the improvement in the performance of discrete power devices. "It's getting better every year and silicon performance is now an order of magnitude better than a decade ago. Gallium nitride technology will push this even further."
However, he noted that power had to be seen as part of the bigger picture. "We need to understand the systems and the solutions before we can define silicon," he concluded.

Graham Pitcher

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