Low voltage SRAM could save your battery

Fujitsu and its chum SuVolta have been showing off what they have dubbed a memory breakthough which could cut the power requirements of SRAM.

Using the idea it is possible to get ultra-low-voltage operation of SRAM down to 0.425V. It uses SuVolta’s PowerShrink low-power CMOS platform and Fujitsu Semiconductor’s low-power process technology.

According to a press release at the International Electron Devices Meeting (IEDM) being held in Washington DC the problem of controlling power consumption on mobile gear has been baffling boffins for ages, along with curing cancer, finding dark matter, and methods to put out Schrödinger’s Cat.

The press release tells us that the biggest contributor to power consumption is supply voltage and the current power supply voltage of CMOS steadily reduced to approximately 1.0V at the 130nm technology node.

Although there have been shedloads of breakthroughs and we are now at the 28nm node the voltage is still the same and this is one of the biggest obstacles is the minimum operating voltage of embedded SRAM blocks.

Using SuVolta’s Deeply Depleted Channel (DDC) transistor technology, which is a component of the PowerShrink platform and Fujitsu Semiconductor’s process technology, the two outfits have made 576Kb SRAM which can work well at approximately 0.4V.

They did this by cutting CMOS transistor threshold voltage (VT) variation in half which apparently did it no harm.

Fujitsu tells us that the technology works well with existing systems including the lucrative system-on-chip designs.

This is important, because, while other boffins have managed similar battery tricks they have needed to use exotic structures such as the ETSOI and Tri-Gate which is a FinFET technology. As you would expect, ETSOI and FinFET are about as compatible with existing design and manufacturing infrastructures as a Great White shark and would require some major surgery to chip design, and a bigger boat.

It is not clear when we will see the technology being used, however it does give us an alternative to Tri-Gate, which had been seen as the way forward.