DDR4 Design Considerations - EEWeb

EEWeb PULSE INTERVIEW
How did you get into
engineering?
I always loved math and science, even
as a young boy. I applied to several
of the top science and engineering
schools, because I wanted to be
involved in something related to
science. I chose engineering at
Princeton over CalTech and MIT, and
I joined the Department of Aerospace
and Mechanical Sciences. In that
department, I studied a large variety
of engineering and science courses,
and found them all very interesting. I
took a program in engineering physics
because I found physics especially
fascinating. It is so fundamental to
understanding the way the universe
operates. That actually led me into
solid-state technology and eventually
into power semiconductors.
In 1978, I joined International Rectifier,
which was my first permanent
position, and worked on the
development of their first family of
power MOSFETs. From there I moved
into solid-state optocoupled relays
and high-voltage and high-power ICs,
where I was involved in process and
From there I came to Fairchild, where
I was able to continue to work in
the power area with a world-class
company. I was also able to get
involved with the mobile business and
began working with the technology
development team to improve the
integrated circuit processes. Since
I’ve been here at Fairchild, I’ve put a
lot of focus on improving the power
device technology across the range
of power and high-density power
packages and modules.
Could you give us a little
history of Fairchild?
Fairchild’s history goes back to 1957.
Many credit the origins of Silicon
Valley to the founders of Fairchild.
Many believe that Robert Noyce’s
silicon integrated circuit launched
the Information Age. From our origins
until now, we continue to be thought
of as leaders and innovators in the
industry.
From the original Fairchild, our
leadership spun-off into other
companies, including National
“Our IP is inside virtually
every smart phone in the
world, and we ship more than
3 billion units per year to
handset and tablet OEMs.”
technology development as well as
product design. In addition to power
devices, I was spending a lot of time
creating package technologies and
IC designs. I eventually became the
Vice President of R&D at International
Rectifier and held that position from
1989 until 2007.
Semiconductor, Intel, AMD, LSI
Logic and many others. In the
1980’s, Fairchild was acquired by
Schlumberger, and then National in
the early 1990s. Then, in 1997, Fairchild
was spun back out from National as
a stand-alone brand and company.
At that time, Fairchild’s offerings
included the rapidly growing power
MOSFET business, standard logic,
standard linear, analog switches, and
a variety of other analog and discrete
product lines.
The re-formed company went on to
acquire the power semiconductor
businesses of Harris and Samsung,
which added factory locations in
Pennsylvania and Korea. This brought
high voltage power discretes and
high voltage analog ICs, as well as
automotive products into the portfolio.
Fairchild has its headquarters
in San Jose, a major IC fab and
administrative office in Portland,
Maine, with other fab locations in
Pennsylvania, Utah, and South Korea.
Our internal assembly sites are in
China, Malaysia and the Philippines.
In addition, we have several major
wafer fab foundry and assembly
subcontractor relationships. Our
factory in Suzhou, China is a worldclass
power packaging and power
module manufacturing center. We
continue to push the state of the art in
power and mobile applications and
technologies.
What are of some of Fairchild’s
main products?
In broad terms, our offerings fall
into two main categories - power
semiconductor solutions and mobile
semiconductor solutions. In mobile,
Fairchild is a mobile technology leader,
offering an unmatched portfolio of
analog and power technologies
in both standard and customized
semiconductor products for mobile
applications. These include ICs that
offer combinations of analog switches,
load sensing, power management,
audio, lighting, communication, and
sensors, among other functions.
Our IP is inside virtually every smart
phone in the world, and we ship more
than 3 billion units per year to handset
and tablet OEMs. We are also adding
MEMS inertial sensors to our portfolio
of mobile offerings.
In our power portfolio, we have
devices that start at about 12-volts
and go to about 1400-volts. This
includes one of the main families, our
PowerTrench(R) MOSFETs, which
are lower voltage devices in the under
200-volt range. We have a MOSFET
technology that few other companies
have, called shielded-gate technology,
which greatly improves the power
density, switching performance, and
efficiency of trench power MOSFETs.
That’s definitely an area of a lot of
interest. In higher voltage areas, we
have a strong lineup of super junction
MOSFETs in the 600-650V range.
In addition, we have some leading
technologies in AC to DC converters
up to 1 kilowatt, and motor drives
up to 5 kilowatts. For higher power
levels, we have our IGBTs. We’ve got
a variety of technologies there—our
latest technology is called field stop
technology. We have leading edge
performance in 600- to 1200-volt
IGBTs for motor drives, renewable
energy, and industrial and automotive
power train applications.
We are a leading supplier of power
modules that use direct bonded
copper on ceramic and transfer
molded packaging technology. This
technology allows us to manufacture
SPM® smart power modules that
include drive, sense, and protection
features as well as power—with
highly robust cycling performance
and excellent thermal characteristics.
Recently, we announced our newest
technology, silicon carbide. Silicon
carbide technology will be part of the
next generation of power systems,
allowing more power in less space
and the ability to deliver more
performance per unit cost.
For more than 50 years Fairchild
Semiconductor has focused on
“Our largest core mission
concerning energy efficiency
is something that we get very
excited about and we value
the contribution that makes
to society in general.”
customer success. Our commitment
to their success drives us to design,
manufacture, and supply power and
mobile semiconductor technologies
to make home appliances more
energy efficient, enable mobile
device manufacturers to deliver
innovative new features, and boost
the efficiency of industrial products.
Our semiconductor solutions for
automotive, mobile, LED lighting,
and power management applications
help our customers achieve success
every day.
What kinds of products are
you targeting for your silicon
carbide technology?
The device that we led with is a 1200volt
bipolar transistor. We selected
the bipolar transistor to start with
because it has the lowest conduction
loss of any technology, so we can
get the most current out of a given
chip size. It switches extremely
fast—as fast as any device currently
can—so it can also operate at a
relatively high frequency for highpower
applications. Normally, these
applications may run at 5 or 10 KHz,
but with these silicon carbide bipolar
transistors, we can actually take that
up to 30, 40, 50, even 100 KHz in some
applications. We will offer diodes that
complement these transistors, and
we package them in plastic, high
temperature discrete, and power
module packages.
Is there additional drive
circuitry required to implement
this new technology?
Yes. Most designers are not used to
driving bipolar transistors because
they require an input current. One
of the good things about this silicon
carbide technology, compared to
what people remember in silicon
bipolar technology, is that the current
gain is very high, so you don’t have to
put that much current into the base
to get what you want out—the gains
are in the range of 100, typically. The
power loss is not a very big factor—
it’s about a tenth of a percent of the
output power. People do need to
remember how to drive the base of
a power transistor because many are
used to drive MOSFETs and IGBTs,
which are voltage-controlled.
Do you have app notes
or other resources to help
engineers who aren’t familiar
with using these transistors?
Specific to silicon carbide technology,
we have resources from applications
notes, reference designs, evaluation
boards and starter kits, to field
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