Researchers at North Carolina State University have developed new, nonlinear, chaos-based integrated circuits that enable computer chips to perform multiple functions with fewer transistors. These integrated circuits can be manufactured with “off the shelf” fabrication processes and could lead to novel computer architectures that do more with less circuitry and fewer transistors.
Moore’s law states that the number of transistors on an integrated circuit will double every two years in order to keep up with processing demands. Previously this goal has been addressed by shrinking the size of individual transistors so that more could be added to the chip. However, that solution is quickly becoming untenable, and the semiconductor industry is looking for new ways to create better computer chips.
“We’re reaching the limits of physics in terms of transistor size, so we need a new way to enhance the performance of microprocessors,” says Behnam Kia, senior research scholar in physics at NC State and lead author of a paper describing the work. “We propose utilizing chaos theory – the system’s own nonlinearity – to enable transistor circuits to be programmed to perform different tasks. A very simple nonlinear transistor circuit contains very rich patterns. Different patterns that represent different functions coexist within the nonlinear dynamics of the system, and they are selectable. We utilize these dynamics-level behaviors to perform different processing tasks using the same circuit. As a result we can get more out of less.”
Kia and NC State colleague William Ditto, professor of physics and dean of the College of Sciences, worked on the conception, design, development and fabrication of an integrated circuit chip that contains working nonlinear circuits to perform multiple different digital computations.
Traditionally, transistor-based circuits perform one task each. Computer processors operate by routing each instruction and its operands to the appropriate transistor circuit on the integrated circuit that implements that specific instruction. In Kia’s design, the transistor circuit can be programmed to implement different instructions by morphing between different operations and functions.
“In current processors you don’t utilize all the circuitry on the processor all the time, which is wasteful,” Kia says. “Our design allows the circuit to be rapidly morphed and reconfigured to perform a desired digital function in each clock cycle. The heart of the design is an analog nonlinear circuit, but the interface is fully digital, enabling the circuit to operate as a fully morphable digital circuit that can be easily connected to the other digital systems.”
The researchers have produced an alternative approach for computing that is compatible with existing technology and utilizes the same fabrication process and CAD tools as existing computer chips, which could aid commercial adoption.
“We believe that this chip will help solve the challenges of demands for more processing power from fewer transistors,” Kia says. “The potential of 100 morphable nonlinear chaos-based circuits doing work equivalent to 100 thousand circuits, or of 100 million transistors doing work equivalent to three billion transistors holds promise for extending Moore’s law – not through doubling the number of transistors every two years but through increasing what transistors are capable of when combined in nonlinear and chaotic circuits.”
“We are nearing commercial size and power and ease of programming in our evolving designs that could well be of significant commercial relevance within a few months with our three month design/fabrication cycle of improvements and implementations,” Ditto says.
A microchip containing 1,000 independent programmable processors has been designed by a team at the University of California, Davis, Department of Electrical and Computer Engineering. The energy-efficient “KiloCore” chip has a maximum computation rate of 1.78 trillion instructions per second and contains 621 million transistors.
The KiloCore was presented at the 2016 Symposium on VLSI Technology and Circuits in Honolulu on June 16.
“To the best of our knowledge, it is the world’s first 1,000-processor chip and it is the highest clock-rate processor ever designed in a university,” said Bevan Baas, professor of electrical and computer engineering, who led the team that designed the chip architecture. While other multiple-processor chips have been created, none exceed about 300 processors, according to an analysis by Baas’ team. Most were created for research purposes and few are sold commercially. The KiloCore chip was fabricated by IBM using their 32 nm CMOS technology.
Each processor core can run its own small program independently of the others, which is a fundamentally more flexible approach than so-called Single-Instruction-Multiple-Data approaches utilized by processors such as GPUs; the idea is to break an application up into many small pieces, each of which can run in parallel on different processors, enabling high throughput with lower energy use, Baas said.
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