The goal of chipmakers has always been to push Moore's Law, squeezing more and more transistors into a smaller space. But what if you could do more with fewer transistors? That's the intriguing potential of HP's memristor, which joins the standard resistor, the capacitor, and the inductors as a fabled fourth integral circuit component.
First envisioned in 1971 by Berkeley professor Leon Chua, a memristor is a device which can vary its resistance based on the magnitude and direction of the voltage of an applied signal. Furthermore, it retains its resistance state even if it is powered off.
Rediscovering Professor Chua's groundbreaking, but largely overlooked work, engineers and researchers at HP Labs dug into the problem of creating a memristor on the nanoscale. In May they finally succeeded, creating the world's first memristor.
This week at the newly created Memristor and Memristor Systems Symposium, in Berkeley, CA the true potential of the unleashed memristor has finally begun to be seen. One thing is clear -- the little device has the potential to rock the entire hardware industry.
When paired with transistors, memristors can be used to create new and unique circuits that function exactly like circuits with many more transistors. The new circuits are much smaller and consume far less power. In short, memristors allow you to do more with less.
Lead researcher Stan Williams, a senior research fellow at HP, states, "We're trying to give Moore's Law a boost."
Indeed, HP's new invention could allow licensed chipmakers to not only continue Moore's law, but to almost instantly leap ahead, shifting Moore's law years ahead. Williams describes this new mentality, stating, "We're not trying to crowd more transistors onto a chip or into a particular circuit. Hybrid memristor-transistor chips really have the promise for delivering a lot more performance."
In the past chipmakers have developed circuit elements consisting of multiple transistors to do the job that a single memristor does. By chopping out these transistors and putting a memristor in their place, the circuit uses less power and is shrunk. HP has demonstrated such a deployment in the first ever working memristor-transistor hybrid chip.
Mr. Williams says making the device was easier than expected. He states, "Because memristors are made of the same materials used in normal integrated circuits it turns out to be very easy to integrate them with transistors."
Mr. Williams and HP researcher Qiangfei Xia led a team which developed the circuit, a new type of field-programmable gate array (FPGA) which uses far fewer transistors by employing semiconductor titanium dioxide memristors.
FPGAs are reprogrammable hardware circuits, one of the hottest fields in computer engineering today. While FPGAs are frequently used by engineers to test their circuit designs on a smaller scale, as they're reconfigurable, they're too expensive, slow, and power-hungry for normal circuits. Typically they are replaced by leaner dedicated circuits based on the optimized FPGA design. Mr. Williams continues, "When you decide what logic operation you want to do, you actually flip a bunch of switches and configuration bits in the circuit. What we're looking at is essentially pulling out all of the configuration bits and all of the transistor switches."
The new memristor-sporting FPGA design is more compact, more affordable, and uses far less power. In short, it could become the first FPGA to be a viable competitor to dedicated silicon circuits. The potential is impressive; imagine buying AMD or NVIDIA's latest graphics card and receiving regular hardware updates to increase performance and remove errata. As Mr. Williams puts it, "If our ideas work out, this type of FPGA will completely change the balance."
Aside from traditional processing circuits, memristors are also very promising for flash memory, and could greatly reduce its cost.
HP researchers say that the biggest obstacle to memristor circuits is the lack of familiarity among engineers with the device. However Mr. Williams and others at HP assure that the public will see memristor circuits within three years, and that the device has the potential to eventually transform the entire computing industry.