One long-term trend that shows no sign of abating is the move towards smaller
and smaller electronic equipment. Desktop
machines become laptops and then tablets.
Phones squeeze more and more features into
ever-thinner packages. X-ray machines that
formerly required a dedicated room are now brought
to patients on carts. New applications in industrial
automation, medicine, and even the military are also
following the same pattern.
We’ve all heard about Moore’s Law and the huge
increase in the density of transistors on a single
integrated circuit - Intel’s 4004 came in at 192
transistors/mm2 compared to 8. 4 million/mm2 in
the current-generation Xeon Haswell-EP - but that’s
only part of the picture. The trend towards packing
more technology into a smaller space imposes severe
constraints on designers across the board, from
connectors to batteries to antennas.
In this article we will discuss a few of the components
that have arisen in response to this challenge, as well as
some applications that smaller sizes have made possible.
Portable equipment and emerging Internet of Things
(Io T) applications such as home automation, automatic
meter reading, and wireless security have led to a
proliferation of miniature antennas for cellular M2M,
GPS, as well as WPAN and WLAN applications such as
Bluetooth, Wi-Fi, WiMAX, and ZigBee. Antenova, for
example, offers their gigaNova line: a sample product
is the Fusca 2.4GHZ SMD antenna, which measures 4
mm x 3 mm x1.1 mm and claims 65 percent efficiency
at that frequency.
The trend towards miniaturization applies to radar
systems, too. Witness the May 2015 announcement by
Google’s Advance Technology and Progress (ATAP)
group of Project Soli, a new interaction sensor that uses
radar technology to capture movements and gestures of
the human hand, the goal is to interact with wearables
and other Io T devices. The Infineon radar sensor
operates at 60 GHz ( 5 mm wavelength), and has a range
of 0.05 – 5 m and a field of view of 180º. The demo
system displayed uses an array of 2 x 2 microstrip patch
antennas; the board, including antennas, measures less
than 1” x 1”, making it suitable for use in wearables.
In a portable devices such as smartphones and tablets,
space is at a premium, but you still have massive
amounts of data to transfer between boards. In response,
manufacturers have developed ultra low-profile
microminiature Board-to-Board (BtB) connectors which
feature high pin-count and small size. The interconnect
medium is usually Flexible Flat Cable (FFC) or Flexible
Printed Circuit (FPC).
For example, TE Connectivity offers a 0.35 mm fine
pitch stackable BtB connector with a body width of only
1.85 mm and height as low as 0.6 mm. In RF, the Molex
SSMCX is a super small micro-coaxial (MCX) connector
developed for miniature radio and antenna applications.
Operating up to 10 GHz, it’s 30 percent smaller than
the predecessor MMCX (micro-miniature coax). The
first application is an IEEE 802.11x radio and antenna
for a notebook computer.
Apart from the mobile phone industry, another driving
force in the downsizing of batteries is the medical field;
miniature batteries with high volumetric efficiency are
widely used in implantable medical applications such as
neurological catheters, cardiovascular monitoring, and
retinal or cochlear implants.
Implantable batteries employ a range of chemistries,
including Lithium Manganese Dioxide (Li/MnO2),
Lithium Thionyl Chloride (Li/SOCI2), Lithium Carbon
Monofloride (Li/CFx), and Lithium Ion (Li-ion);
EaglePicher’s smallest Micro Cell occupies 0.1cc and
weighs 0.1 g. Using Li/MnO2 chemistry, it outputs 2.8V
and has a capacity of 2.5mAh.
For wearables, Panasonic’s cylindrical Li-Ion CG-320
is 3. 5 mm in diameter and 20 mm in length, making it
Drive Miniaturization Of
By Paul Pickering, Technical Contributor