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Technology Stocks : LAST MILE TECHNOLOGIES - Let's Discuss Them Here
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To: Warren Gates who started this subject12/13/2000 8:03:23 PM
From: rr_burns   of 12823
 
IBM research doing silicon-germanium (si-ge) chip research around hiperlan and 802.11a:

research.ibm.com

Note the voltage levels and the "width" over which
tuning took place.



..rr
>>>>>>>>>>>>>
Speed in SiGe
The key to the advances is the replacement of gallium arsenide
(GaAs), the high- frequency substance normally used in chips
that contain VCO circuits, with silicon germanium (SiGe). This
compound not only offers high speed, it enables high levels
of integration. In this particular case, the VCOs are fully
monolithic and contain no external components such as
inductors and varactor diodes!

Important architecture
Equally important is the fully-differential architecture involved
in the VCOs' design. This architecture minimizes noise
coupling from digital parts of a highly-integrated chip into a
sensitive analog VCO. The added circuitry of a fully
differential architecture typically comes at the cost of
increased power levels, but SiGe achieves this result with
minimum increase in power consumption.

Successful test
A significant trial of the new technology came recently when
an IBM VCO was tested at 17.1 GigaHertz, an ultra-high
transmission frequency recently allocated for wireless uses in
Europe (HiperLAN). The record-setting VCO, operating on a
single 3.3V supply, could be tuned over a 600 MHz range and
exhibited phase noise of -104 dBc/Hz at a 1 MHz offset from
center with an output power of -5 dBm and dissipating only 65
mW.

Another VCO, tuned for a new American standard of 5.x
GigaHertz (U-NII), has also performed exceptionally well, with a
tuning range of 840 MHz and a phase noise of -115 dBc/Hz at 1
MHz offset at the center frequency of 5.6 GHz.
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