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There are several chip design directions that are starting
to become more visible and mainstream. For some such as lower power consumption
the goal is clear. However, the implementation details are varied. For others
they are nice-to-have—the vitamin vs. the pain killers-- the real
compelling, got-to-have. A quick look on various design approaches...
Contributed by Hal Daseking
- Power, Power,
Power, the story goes that increased integration of
functions such as video, audio, & FMC/phone on the same chip, will
significantly increase energy consumption. Not only will there be more
functions, but they will be “on” longer— for example, after
making a phone call, listening to music for the next hour. It is clear at
the 90 and 65 nanometer nodes energy reduction will be the driving
performance criteria! Portal Player (IPod’s platform) recently
introduced “Preface” for notebooks users. When the notebook is
off the Preface/SoC is always-on, allowing immediate access to email,
contacts, music, etc. Users can use Preface for tens of hours AFTER the
laptop’s battery is too low to run the laptop. –integration, integration,
integration. Preface will be available with MS- Vista- OS.
- SoC stages of
development: SoC development has various
stages and process steps. The traditional one- going from FPGA (PoC) then
to SoC and the emerging style of FPGA to 130nm to 90nm process. The 130nm
design is almost a proof of concept that is usable, and provides quick
time to market, and some revenue. It appears that the advantages
going to 90/65 nanometers are integration, where throughput/low power
consumption is achieved by multiprocessing (area maybe larger).
- Scaling and
multiprocessing- On the embedded side,
multiprocessing has won and is now common in most SoCs such as Nexperia,
Xscaler, Nomadic, OMAP, DaVinci, etc. Multiprocessing provides the added advantage
of significantly reduced energy consumption, through processor hibernation
such as the Portal Player example given above. ARM11 MPcore has a IEM, Intelligent
Energy Manager that can achieve 50% power savings through shutting down unused
processors something a uniprocessor would find difficult.
- Configurable
Blades- For compute intensive applications i.e. Supercomputers
there is a new trend in “FPGA” configurable processor/blades. Instead
of having a homogenous processor/blade, which is popular today, the idea
is to add an FPGA and the interconnection to support application/blades
that are tailored to the application. Celexica just recently announced that
they are working with Cray/HP to develop a method to accelerate portions
of applications through C to FPGA. Instead of using multithreading to
speed up processing or even multiprocessing, configurable hardware
provides the best price/performance.
- Programmable
vs Performance- There will most likely always
be an ARM/MIPS processor for software hosting, and GUI/control. The degree
of programmability of the compute “compression” and analysis portion
of the product depends on the application and its architecture. Therefore
the tradeoffs will be between a heterogeneous processor approach, and a
hardware accelerator approach. The most common reasons for programmability
are: 1) flexibility for accommodating changes in early standards
when the “paint is still wet”, 2) Universal platform to accommodate
more applications and therefore increase chip volume and 3) IDM options-
where certain product markets only require certain portions of the
standard—for example SDR, software defined radio, or HD vs SD video-
H.264. Most algorithmic-IP is based on a programmable architecture to accommodate
customer specific changes and to use with multiple associated algorithms.
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Hardware accelerators will perform
orders of magnitude better than a programmable solution and for cost alone will
eventually become the production chip design. Most programmable SoCs will also
have a portion of custom logic.
- Successful IP
companies: the successful IP companies have established a
wide market appeal on a well defined product. (ARM, MIPS, Ceva, Rambus,
Virage Logic, Starcore, Imagination Technology, and many small IP
providers such as Ocean Logic). IP business conflict- universal appeal to
get market size, vs. specific implementation to achieve individual
customer success. IP provider targets “commodity” products,
which are low-price (typically $50k), or lower margins because of more
support required to customize their IP- a real conundrum.
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