Rf Tx/Rx Path And Test Points; Gsm Tx/Rx Path And Test Points - Asus M530w Service Manual

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17. RF Tx/Rx Path and Test Points

How RF signal is transmitted and received between components on Halley
PCB is explained in this section. It is important to realize RF transmission path
(Tx) and receiving path (Rx) before starting out to repair NG PCB, because
engineers need to choose proper test points which assist us to distinguish where
the problem is. The following paragraphs describe both Tx and Rx path in
GSM and WCDMA bands. The related test points are listed in the following
figures.

17.1 GSM Tx/Rx path and test points

GSM Tx path
Transceiver, RF6001 (U900), receives IQ signals coming from baseband,
and output signals of RF6001 Pin22 and Pin23 are transmitted into the buffer of
receiver, RF2722. Then RF2722 Pin12 and Pin13 emit the low band signal
(GSM900) and high band signals (DCS1800 or PCS1900) separately.
In the low band, output signal from RF2722 Pin12 passes through C917,
attenuator (U903) and RF3166 (U904) Pin7, power amplifier, sequentially.
Transmission and receiving switch (U902), also named T/R switch, gets the
amplified signal from RF3166 Pin23 via matching circuits. RF signal coming
from T/R switch Pin15 is transmitted to connector (Con6) and radiated via the
GSM antenna of Halley.
In the high band, output signal from RF2722 Pin13 passes through C243,
attenuator (U905) and RF3166 (U904) Pin1, power amplifier, sequentially.
Transmission and receiving switch (U902), also named T/R switch, gets the
amplified signal from RF3166 Pin30 via matching circuits. RF signal coming
from T/R switch Pin15 is transmitted to connector (Con6) and radiated via the
GSM antenna of Halley.
GSM Rx path
RF signals, receiving from base stations via the GSM antenna, pass
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