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reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
July 6, 2010
AN1559.0
WLAN Application Setup
The following setup should be used for testing QHx220
noise cancellation ability for a WLAN application. It is
important to maintain the identical core setup used in the
“WLAN Optimization Setup (Static Coupling Channel)”
section on page 17. Otherwise, the optimization values
will not be valid.
Begin with the aggressor source (signal generator) and
QHx220 board powered off. Turn on the WLAN simulator
and WLAN receiver and record the receiver’s signal
quality parameters (C/N, etc.). Find the weakest WLAN
signal power level that will still maintain a WLAN link.
Next set the aggressor signal generator to the same
WLAN frequency and set the power level to roughly 10dB
above the peak of the broadcast WLAN signal. The
aggressor signal needs to be high enough to show
degradation of the receive signal strength reported by
the WLAN receiver. Remember not to exceed ~ -45dBm
at the input of the QHx220. Once an aggressor power
level is found that degrades the receive signal strength
reported by the WLAN receiver, turn on the QHx220
board and set the optimized I and Q values that were
determined in the “WLAN Optimization Setup (Static
Coupling Channel)” section on page 17. This should
result in a <15dB recovery of the receive signal strength
power reported by the WLAN receiver if the board was
optimized correctly. However, since the setup was slightly
modified from the original optimization setup, it should
be possible to fine tune the QHx220 to improve the
in-band noise cancellation. Please note that any changes
to the cable lengths or slight impedance changes will
slightly impact the optimal gain and phase of the
QHx220. Therefore, in the WLAN application setup,
adjust the gain and/or phase one step at a time and
monitor the WLAN receiver sensitivity (or any other
signal quality parameter (i.e. C/N, etc.). Continue to
adjust the gain and phase one step at a time until no
further improvement to the receiver sensitivity can be
achieved.
Q:ACTIVE
Q:ACTIVE Technology is behind Intersil’s ability to insert
its ICs inside radios, automotive infotainment systems,
satellite broadcast equipment, and various consumer
electronic devices such as GPS units, cell phones, and
portable gaming systems. By doing so, Intersil achieves
the ability to reduce electromagnetic interference by as
much as 30dB. This breakthrough in radio sensitivity
allows for several signals to run simultaneously and
enables new technologies such as mobile TV on hand
held games, cell phones, and in automotive systems.
FIGURE 19. WLAN TESTING SETUP DIAGRAM
WLAN
AGGRESSOR
PATH
SIGNAL
GENERATOR
WLAN
SIMULATOR
QHX220
WLAN
RECEIVER
CANCELLATION
NODE
WLAN RECEIVE PATH
POWER
SPLITTER
ATTENUATOR PAD
TO SET COUPLING LOSS
POWER
SPLITTER
Application Note 1559
