December 2010 Supplement S
45
most suitable for close-range applications of gigabit
wireless data transfer.
Several emerging 60 GHz standards, including
WirelessHD [5], IEEE 802.15.3c [6], and ECMA 387 [7],
are targeted toward short-range wireless personal area
networking (WPAN) such as high definition streamed
multimedia and high-speed kiosk data transfers. Cur-
rently, the two most popular 60 GHz standards, IEEE
802.15.3c and WirelessHD, will primarily deliver Gb/s
streamed video and audio. Both standards are com-
pleted (WirelessHD finished a second revision for
higher rates in May 2010) and WirelessHD-certified set
top boxes for home multimedia streaming are already
available in retail outlets.
Next-generation wireless local area networking
(WLAN) will also exploit 60 GHz spectrum through
the development of the IEEE 802.11ad and WiGig
standards [8]–[11]. This is supported by WiFi com-
panies who recognize that microwave band spectral
resources are insufficient for next-generation applica-
tions, even with increased modulation efficiency and
extended antenna resources (the approach taken by
IEEE 802.11ac to increase data rates of IEEE 802.11n).
Because WiGig is privately developed through an in-
dustry consortium, it has already published version
1.0 in May 2010, with consumer products expected to
roll-out in late 2011, whereas IEEE 802.11ad is target-
ing final approval by December 2012. As a testament
to the commitment of 60 GHz technology into WLAN
markets, the WiFi and WiGig standards have recently
announced interoperability agreements [12].
In addition to providing massive bandwidth for
future WPANs and WLANs, adoption of wireless
connectivity will soon be necessary, which is evident
from the consideration of skin and proximity effects,
substrate losses, and dispersion of wired intercon-
nects at carrier frequencies of 60 GHz to hundreds of
GHz. These impairments will make wired solutions
extremely difficult and/or expensive for future mas-
sively broadband devices
with data rates from tens
to hundreds of gigabits per
second [13], [14]. For exam-
ple, on-chip and in-package
antennas used in 60 GHz
links may be the predeces-
sors to wireless intercon-
nects in personal computers.
The maximum bit-rate of a
wired interconnect of cross-
sectional area A and length
l is approximately 10
6
A/l
2
[13], indicating that the lon-
gest wired interconnect that
can support 100 Gb/s with-
out equalization is less than
5 mm in length. Ironically,
massively broadband devices operating at 60 GHz
and above are likely to have dimensions greater than
5 mm.
Current Challenges
Antennas
60 GHz chipsets exploit the short-carrier wavelength by
incorporating antennas or antenna arrays directly on-
chip or in-package. For the simplest and lowest-cost
solutions, single antennas are attractive. Single-an-
tenna solutions, however, must overcome the challeng-
es of low on-chip efficiencies (typically 10% or less [14])
and in-package antennas must overcome lossy pack-
age interconnects (standard wire-bonds are limited to
under 20 GHz [15]). For in-package antennas, package
material with low dielectric constants will give the best
gain-bandwidth products [16], but this must be weighed
against other factors, including manufacturing precision
and available interconnect technologies (for example,
wire-bonding, flip-chip, or coupling connections) [17],
[18]. Popular package technologies include low-temper-
ature cofired ceramic (LTCC, P
5 5.9 2 7.7 [19], [20]),
fused silica (P
5 3.8 [21]), liquid crystal polymer (LCP,
P
5 3.
[22]), and Teflon (P
5 2.2 [17], [23]).
High gain on-chip antennas (for example, 10 dBi
gain, where dBi is the gain in decibles with respect to
an isotropic radiator) offer the cheapest solution for
60 GHz communications. One approach is to develop
High-Gain Rhombic Antennas
5 mm
5 mm
Trace
Width
Feed Points
γ
z
x
y
660 µm
Azimuth
Elevation
0
30
60
90
120
150
–180
–150
–120
–90
–60
–30
–4.00
–8.00
–12.00
–16.00
0
30
60
90
120
150
–180
–150
–120
–90
–60
–30
–4.00
–8.00
–12.00
–16.00
φ
Figure 1. Rhombic on-chip antennas and polar plots of their gains [14].
The millimeter-wave band, especially
the unlicensed spectrum at the
60 GHz carrier frequency, is at the
spectral frontier of high-bandwidth
commercial wireless communication
systems.
richyrichy2012-10-07This is a short article introducing 60GHz technology in IEEE magazine 2010; not a textbook or paper.
