A California research team has found a way to increase power on chips without creating heat: micro-capacitors
A potentially major breakthrough has been made that promises to reduce the minimum voltage required to drive a transistor, which could extend Moore’s Law for a while longer and pave the way to ultra low-power computing.
A team at the University of California, Berkeley, has developed a way to provide localised power to processor chips’ transistors to allow less power to drive the processor and reduce heat problems significantly. Low-power, high throughput is the current challenge in green computing.
Cool Capacitance Effect
A processor chip is made of billions of tiny transistors – the on-off switch components that generate the “zeros and ones” that are the core of binary computing. The more transistors packed onto a chip, the greater the processing power, but the density of transistors is reaching a physical maximum – not because they cannot be reduced in size but because of heat problems.
Power intake is constant and this means the heat dissipated by each transistor is also constant, regardless of its size. The more there are on a chip, the hotter the processor gets. This led to processor fans being attached to chip housings when heatsinks began to become less effective. Engineers are now reaching the limit where transistors cannot be reduced in size any more without risking a fire hazard that will burn out the transistors.
The Berkeley researchers have been tackling this problem. They have used ferroelectrics, a class of materials that can hold both positive and negative electric charges, even when the charging voltage is removed. The electrical polarisation of ferroelectrics can also be reversed with an external electric field.
The team has created a power storing device made of ferroelectric-based materials paired with an electric insulator. This is an effective capacitor, an electron-storing component that accumulates, stores and discharges electrical power – similar to the effect of adding a small battery.
The charge accumulated in the ferroelectric capacitor, for a given voltage, is amplified in a phenomenon called “negative capacitance”. The result is a charge that would normally require a higher voltage which, when applied to a bank of transistors would translate into lower minimum voltage required to operate a computer processor – and therefore lower heat production.
More To Come
This could breathe new life into Moore’s Law, which is not really a law but an observation of integrated circuit (IC) development by Intel co-founder Gordon Moore in 1965 which then became the company’s mission. He noted that the number of transistors in ICs doubled every two years or so. Intel’s obsession with maintaining Moore’s Law saw the expansion of transistor capacity from the few thousand on 1970s chips to the massive densities of today.
Sayeef Salahuddin, University of California’s assistant professor of electrical engineering and computer sciences, said there are other potential applications for ferroelectrics in electronics.
“This is a good system for dynamic random access memories [DRAM], energy storage devices, super-capacitors that charge electric cars, and power capacitors for use in radio-frequency communications,” he said.
There is still research to be done to develop the Berkeley breakthrough. “This work is the proof-of-principle we have needed to pursue negative capacitance as a viable strategy to overcome the power draw of today’s transistors,” said Salahuddin. “If we can use this to create low-power transistors, without compromising performance and the speed at which they work, it could change the whole computing industry.”