CPU voltage regulator increases power delivery by 10x

Technology News |
By Rich Pell

The demand for power ultimately comes from the demand for computing, say the researchers, and this demand for highly controlled power has proven to be a limit to chip designers and a major challenge for power electronics engineers. Sending large amounts of power to tiny areas generates heat, which is not only inefficient, but can also be fatal to computer components.

“It has to be extremely efficient with very low noise, precisely controlled to a very tiny area,” says Minjie Chen, assistant professor of electrical and computer engineering and the leader of the Princeton research team. “If the efficiency is not high enough, you will overheat. If the components overheat, you will not be able to deliver the power.”

The researchers, who are working with Intel, Google, and colleagues at Dartmouth College, are focused on developing “smaller, smarter and more efficient power electronics for emerging and important applications.” Although new generations of chips and circuitry draw the most attention, power delivery is an increasingly critical element of computer system design.

Better power delivery is required for smaller smart phones and other devices, more efficient server centers and advanced processors to support increasingly sophisticated artificial intelligence systems, say the researchers, who are also looking beyond computer systems to programmable designs solar power arrays, the smart grid and other critical infrastructure. As a result, the researchers say they have demonstrated a strategy for meeting the industry’s goals in a way that can apply to small systems or scale to meet the needs of massive data centers.

To meet the demands of new computer systems, the researchers had to overcome three challenges: Deliver power to smaller areas to allow microprocessors to sit ever-closer together; operate with high efficiency both to cut costs and to prevent overheating; and switch power among components with blinding speed to match the demands of microprocessors.

“Google and Intel originally asked ‘How do you deliver 10 times more power to a millimeter square of silicon without sacrificing speed or efficiency?’” says Chen.

The researchers say they accomplished all three by rethinking everything from power delivery components to their architecture and control. They used capacitors instead of the traditional method of magnetics to process power, and they built the systems vertically instead of the traditional horizontal construction. Both features introduced significant design challenges, but once the researchers solved those, they were able to deliver a superior system.

“We have tested the efficiency up to full power, and we have tested the dynamics,” says Chen. “It is a fully functioning system 10 times smaller than the best off-the-shelf.”

The researchers built and tested a 780-A vertical stacked CPU voltage regulator with a peak efficiency of 91.1% and a full load efficiency of 79.2% at an output voltage of 1 V with liquid cooling. The switched capacitor circuits operate at 286 kHz and the buck circuits operate at 1 MHz. It regulates output voltage between 0.8 and 1.5 V through the entire 780-A current range.

Their voltage regulator, say the researchers, is the first demonstration of a 48–1 V CPU voltage regulator to achieve over 1-A/mm2 current density and the first to achieve 1000-W/in3 power density.

For more, see “Vertical Stacked LEGO-PoL CPU Voltage Regulator.”


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