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digital signals up to 10 Gbytes/s and RF carrier frequencies in the range of 5 to 14 GHz.
Various passive and active components for the realization of efficient RF-digital
interfaces have been implemented in this design, along with design rules that were
developed for various frequencies.
A voltage-controlled oscillator module has been developed and successfully
demonstrated for 5.8-GHz operation in the INC system. The standard cross-coupled
VCO has been fabricated using a commercial MESFET process without inductors. The
bare die IC has been wire-bonded to the two embedded inductors that were embedded
in the organic substrate. The high-Q inductor helped reduce the phase noise of the VCO
significantly, as explained in Chapter 4. The VCO module integrated in the INC testbed
showed a phase noise of 110 dBc at a 6-MHz offset frequency and –10 dBm of output
power.

5.6 Future Trends
With rapid growth in wireless applications, coupled with the tremendous advances in
the silicon process technologies, one can envision the emergence of a fully integrated RF
CMOS radio on a tiny piece of silicon. However, this is unlikely because of the cost and
technical challenges that include the lossy nature of silicon, low process yields at 45- to
22-nm lithography, and thermomechanical reliability issues. The recent trend has been
the development of multiband and multimode wireless solutions enabling effective
utilization of bandwidth and tuning to the appropriate data rate whenever necessary
and with freedom to use different bands in different countries. Software radios are
emerging as platforms for these multiband, multimode personal communication
systems, and cognitive radios further enhance their flexibility for personal services
through a radio knowledge representation language. Cognitive radio is a paradigm for
wireless communication in which either a network or a wireless node changes its
transmission or reception parameters to communicate efficiently without interfering
with licensed users. This alteration of parameters is based on the active monitoring of
several factors in the external and internal radio environment, such as the radiofrequency
spectrum, user behavior, and the network state. The cognitive radio language represents
increasingly complex knowledge of radio etiquette, devices, software modules,
propagation, networks, user needs, and application scenarios in a way that supports
automated reasoning about the needs of the user. Nonetheless, cognitive radios are
already making headway in the real world. Companies such as Intel for example are
exploring reconfigurable chips that will use software to analyze their environments and
select the best protocols and frequencies for data transmission in highly congested
traffic.
Highly integrated system technologies will be required to reduce the system chip
size. These technology developments include (1) system-on-chip (SOC) in Si and SiGe
with improved performance at the device and circuit level than in the past, (2) stacked
chip approaches separating ICs into individual functional units but realizing the
miniaturization by stacking of thinned chips, (3) embedded thin actives in the package or
board, (4) embedding of discrete passives, and finally (5) embedding of all passive and
active components in thin-film form. The use of embedded thin-film components has
already started on silicon or glass wafer by such semiconductor companies as Philips and
ST, in ceramics by Murata and TDK in Japan, and in organics by a number of package
companies in Japan in partnership with Motorola. The system-on-package is clearly