Ferroelectric RAM
By Our Convergence Bureau | 10 May 2007
FeRAM, or FRAM as the acronym sometimes goes, is a non-volatile (one that still retains it''s contents when it loses power) type of computer memory, which uses a ferroelectric film as the capacitor for retaining data. This kind of memory is still trying to get widespread acceptance in mainstream applications, and in the near future may prove to be a workable alternative to existing flash memory, by exploiting flash memory''s weaknesses to it''s advantage. FeRAM is "better" on account of its low write voltage, faster write speed, and greater write-erase endurance.
How
does it work?
Most of FeRAM technology was developed at Ramtron International,
with Fujitsu being the major licensee and the largest volume producer of FeRAM
chips in the world. FeRAM relies on a ferroelectric film for retaining data without
power supply. It leverages the ability to
(a) align / polarise semi - permanent
electric dipoles (a separation of positive and negative charge) by way of an external
electric field, which retain this polarisation when the electric charge is removed,
and
(b) Read / retrieve / decipher / interpret this polarisation as a "0"
or a "1" - as the two possible values in each storage cell.
Typically, "1`" is the retained negative polarisation, and "0" the positive.
Advantage
Power Consumption
Unlike the more popular and commercially available DRAM
(dynamic RAM), which needs a "refresh" a number of times per second
using a constant power source, FeRAM retains readable polarisation in the absence
of a power source.
Present flash memory uses a method similar to FeRAM
to push electrons across a high quality insulating barrier, where they get stuck
on one terminal of a transistor. Comparatively, flash memory needs a much higher
voltage than FeRAM, which needs only marginally higher power to "write"
than what it needs to "read".
It''s
all about Speed
Speed is a relative measure. To get a clearer picture,
let''s look at FeRAM vs. DRAM.
DRAM''s limitation is the rate at which current in its cells can be stored (for writing) or drained (for reading). This depends directly on the capacity of control transistors, the lines carrying the power to each individual cell, and the resultant heat generation in the process.
FeRAM instead relies on the physical movement of atoms, responding to an external field that is phenomenally fast and settles in about a nanosecond. Theoretically, this could point to FeRAM being faster than DRAM, and maybe even outpace flash memory, as flash memory needs a charge build up to write. FeRAM needs no such build up (a.k.a. the low power consumption feature). Present FeRAMs are about a 100 times faster than the 1 millisecond it takes flash memory to write a single bit of info.
Applications
Needless
to say, FeRAM has possibilities that threaten the current domination of other
forms of DRAM / flash memory in commercial applications. Present applications
include
- Meters: electric / water / gas consumption.
- Automotive: Airbag deployment, car radios which remember your favourite radio station presets, cruise control systems, engine sensors and microprocessors that track performance and / or maintenance over time, instrument panel data (digital odometers being the most obvious), on-board navigation/GPS equipment, and of course toll tag technology to pay highway tolls.
- Communications:
phones, radio sets, cell base stations, data loggers and portable GPS devices
to name a few.
- Consumer
electronics: Plasma and LCD TVs, set top boxes for starters.
- Computers:
office equipment - phtocopy machines, faxes, etc., network storage, and many
more.
- Industrial:
lifts / elevators, hotel room access systems (electronic locks), instrumentation
applications, medical equipment monitors, assembly lines, the possibilities are
endless.
- Others: ATMs, digicam memories, point of sale machines, vending machines, and handheld gaming devices
Most definitely, this technology has the potential of redefining product performance in applications that use flash and other types of memory. It may even end up advancing a number of other applications in future as well. Clearly, the wait and watch games have begun.
