Recent discoveries in the field of computer engineering have made waves in the technological community. According to Paul Franzon, a professor of computer and electrical engineering and senior researcher on the Double Floating-Gate Field Effect Transistor (DFG FET) project, two of the main applications of this technology can directly impact both environmentally conscious data servers and anyone who uses a laptop.
According to Neil Di Spigna, an assistant research professor who worked on the project, the integration of volatile and non-volatile memory eliminates communication lag.
“When I use my laptop, if I step away from it for a second, I could’ve hibernated the computer. I think it could extend laptop life and power savings tremendously,” Di Spigna said.
The DFG FET is a new type of computer memory. It is designed to utilize both the speed of volatile memory and the storage ability of non-volatile memory, while avoiding the pitfalls of both. While most current volatile memory uses a single floating gate, the DFG FET uses two floating gates to enable both modes of operation simultaneously.
Current DRAM memory is volatile: it requires a constant flow of electricity to keep its data. When a user wants to save their session, they have two options; standby, or hibernatie
“[The DFG FET] gets rid of the bottleneck,” Franzon said. “It’s all internal.”
According to Franzon, DFG FET differs from current RAM by holding data without power by copying it from the volatile memory into the nonvolatile component–a near instant process.
“We just do a read/write cycle row by row inside the memory and in a matter if milliseconds we’ve written all the bits to the non-volatile state,” Franzon said. “When you turn it back on, you can just start using it. You don’t have to write it back to the volatile state. So it’s quick to go into hibernate and it comes out of it instantly.”
According to Franzon, another major role for the DFG FET is in server farms. In a paper by Google on server farm efficiency, researchers found that servers use electricity disproportionately to the amount of network traffic. For example, a server doing nothing still consumes around 50 percent of peak power and, according to Franzon, one reason is the inability to turn the memory off.
“You have to keep refreshing [memory] or it loses its state,” Franzon said. “It needs charge and has to be refreshed every 64 milliseconds. The idea [with the DFG FET] is instead of sitting there forever refreshing your memory, when parts of it are in a mode where they’re not changing, you write it to the non-volatile state. Once it’s in the non-volatile state you can actually turn it off.”
According to Franzon, data servers alone consume 1.2 percent of all electrical power produced in the U.S., and one third of that is attributed to memory and its overhead.
“We’re addressing that third,” Franzon said. “This sort of thing has real potential to reduce electricity–decrease the carbon footprint of computing.”
The DFG FET is the result of a curiosity-driven research project between Franzon, Di Spigna, and Daniel Schinke. Schinke, a post-graduate student from Germany at the project’s inception, is now a University graduate with a PhD in electrical engineering. According to Franzon, the project evolved over time and was the result of the three bouncing ideas off each other.
“This is actually curiosity-driven research as opposed to goal-driven,” Franzon said. “In Neal [Di Spigna]’s PhD, he looked at different ways of making floating gates. Three years ago I wrote a proposal to the National Science Foundation to explore that and the applications. Daniel [Schinke] started working on that effort for his PhD… Neil pointed out, ‘Hey, you could have two floating gates here and there might be additional things we can do with that.’ Then Daniel [Schinke] started looking at the idea of a unified memory we iterated on that as a group many times to get to what you see in that [IEEE] paper.”
“This was an invited paper to the magazine; it’s gotten a lot of good feedback,” Di Spigna said.
“There has been an article out, even EE Times and BBC News Technology caught on to this article,” Schinke said. “When I was in Germany, I even read an article about this new technology in Germany in my German newspaper. It was very cool.”
According to Di Spigna, a grant from the NSF and an award from the Semiconductor Research Corporation funded the project. The NSF grant was initiated in 2008, worth a total of $406,250.
Chips have been fabricated in the University’s Nanofabrication Facility in Centennial’s Monteith Research Center, according to Di Spigna. The next priority is to test the device’s lifespan and to work toward fabricating the exact chip described in the paper.
“Daniel [Schinke] spent a lot of time engineering these devices,” Di Spigna said. “Actually fabricating what he has engineered, there is a little bit of a process that that goes through. As we continue to have good results, we will continue to move toward this target device.”
According to Franzon the group is in slow discussion with some companies in marketing the FTP.
