For instance, if mobile handsets
could support more bandwidth,
Google maps could download fast
enough to provide real-time information while driving, and still leave
enough power to make a phone call
(see Figure 1). RF physical layer integration on par with that of the op
amp will enable the types of collaboration necessary to continue integrating wireless services into the full
range of daily activities. But how do
we get there?
RF PLUG AND PLAY
As a matter of fact, this concept of
RF “plug-and-play” is already becoming a reality. For instance, location-based services in mobile phones have
been eagerly anticipated for almost a
decade. Although CDMA phones
have incorporated GPS-based base-
band signal processing since their inception, the need for high receiver
sensitivity (roughly – 160 dBm) and
near-frequency high-power interference from cellular signals created a
natural impediment to small footprint, low-power GPS solutions for
full-featured, location-based consumer services. However, this all
changed with the introduction of high
performance, low power consumption, integrated RF physical layer
GPS receivers that are capable of coexistence with cellular networks (see
Figure 2). Their release has been the
catalyst for rapid integration of GPS-based navigation services in mobile
phone platforms.
The need for WLAN functionality
in handheld devices led to the convergence of WLAN, FM radio, GPS
and Bluetooth technologies onto single digital signal processing platforms. We are now seeing multi-function RF front-ends—combining the
power amplifier, low noise amplifier,
RF switch and filtering in a single
package, creating multi-mode RF signal processing solutions. These higher levels of integration and modular-ization are made possible by semiconductor technologies such as silicon
germanium (SiGe), which enables
single-chip mode-programmable RF
front-ends with the RF performance,
low power consumption and small
form factors required for thin, dis-play-centric devices similar to Apple’s
iPhone. The end result of RF plug-
®
and-play integration will be a rich
suite of wireless connectivity-based
applications—in-car navigation systems with roadmaps showing location
through GPS, local traffic using FM
radio data system (RDS), which is
linked to the car’s audio system via
Bluetooth, and the ability to upload
audio and video entertainment via
WLAN.
The migration of RF signal processing design from “device-centric”
to “function-centric” lies at the core
of the evolution of the RF physical
layer from “black art” to functional
block. Today’s technologies are driving the trend for multiple radios in a
system, supporting multiple trans-mit/receive chains and frequency
bands. The net result is, without continuing innovation in functional integration of the RF physical layer, wireless connectivity solutions will simply
