Corporation (TOKYO:6502) continues to build on its commitment to
promoting the Internet of Things and Big Data analysis with development
of a Time Domain Neural Network1 (TDNN) that uses an
extremely low power consumption neuromorphic semiconductor circuit to
perform processing for Deep Learning. TDNN is composed of a massive
number of tiny processing units that use Toshiba’s original analog
technique, unlike conventional digital processors. TDNN was reported on
November 8 at A-SSCC 2016 (Asian Solid-State Circuits Conference 2016),
an IEEE-sponsored international conference on semiconductor circuit
technology held in Japan.
“Committed to People,
Committed to the Future”
Deep learning requires massive numbers of calculations, typically
executed on high performance processors that consume a lot of power.
However, bringing the power of deep learning to IoT edge devices, such
as sensors and smart phones requires highly energy efficient ICs that
can perform the large number of required operations while consuming
extremely little energy.
In von Neumann type2 computer architecture, most energy is
consumed moving data from on-chip or off-chip memory devices to the
processing unit. The most effective way to reduce movement of a datum is
to have massive numbers of processing units, each dedicated to handling
only one datum that is located close by. These datum points are given a
weight during conversion of an input signal (e.g. an image of a cat) to
an output signal (e.g. the recognition of the image as a cat). The
closer the datum point is to the desired output, the higher the weight
it is given. The weight provides a parameter that automatically guides
the deep learning process.
The brain has similar architecture, in that the strength of coupling
between neurons (weight data) is built into synapses (processing units).
In this case, synapses are connections between neurons and each has a
different strength. That strength (weight) determines the signal that
passes the connection. In this way, a synapse executes a kind of
processing. This architecture, which can be called as fully spatially
unrolled architecture, is attractive, but it has an obvious
drawback—replicating it on a chip requires a massive number of
arithmetic circuits that quickly becomes too large.
Toshiba’s TDNN, which employs time-domain analog and digital mixed
signal processing (TDAMS3) techniques developed in 2013 allow
miniaturization of the processing unit. In TDAMS, arithmetic operations,
such as addition, are performed efficiently by using the delay time of
the digital signal passing the logic gate as an analog signal. Using
this technique, the processing unit for deep learning can be composed of
only three logic gates and a 1-bit memory with the fully spatially
unrolled architecture. Toshiba has fabricated a proof-of-concept chip
that uses SRAM (static random access memory) cell as the memory and that
has demonstrated recognition of handwritten figures. The energy
consumption per operation is 20.6 fJ4, which is 1/6x better
than previously reported at a leading conference before5.
Toshiba plans to develop TDNN as a resistive random access memory
(ReRAM) in order to further improve energy and area efficiencies. The
goal is an IC that realizes high performance deep learning technology on
TDNN: Neural network using time-domain analog and digital mixed signal
Von Neumann type: The standard and most widely used computer
architecture. The architecture loads data from memory devices to the
processing unit for processing.
TDAMS: An analog signal processing technique that uses the delay time
of a digital signal passing logic gates as an analog signal. Developed
by Toshiba. (reference: http://www.toshiba.co.jp/about/press/2013_02/pr2101.htm)
20.6fJ: Equivalent to the performance of 48.6 trillion operations in 1
second with 1 W of power consumption.
ISSCC 2016 (International Solid-State Circuits Conference 2016) paper
About Toshiba Corporation
Toshiba Corporation, a Fortune
Global 500 company, channels world-class capabilities in advanced
electronic and electrical product and systems into three focus business
fields: Energy that sustains everyday life, that is cleaner and
safer; Infrastructure that sustains quality of life; and Storage
that sustains the advanced information society. Guided by the principles
of The Basic Commitment of the Toshiba Group, “Committed to People,
Committed to the Future”, Toshiba promotes global operations and is
contributing to the realization of a world where generations to come can
live better lives.
Founded in Tokyo in 1875, today’s Toshiba is at
the heart of a global network of 550 consolidated companies employing
188,000 people worldwide, with annual sales surpassing 5.6 trillion yen
(US$50 billion). (As of March 31, 2016.)
To find out more about
Toshiba, visit www.toshiba.co.jp/index.htm