RH-6
Company Confidential
7 - RF Description & Troubleshooting
CCS Technical Documentation
Page 20
Copyright
©
2003 Nokia Corporation.
Issue 1 10/2003
Company Confidential
The EGSM900 output is controlled by the power control loop. From the EGSM900 output
of the PA the RF signal is fed through the directional coupler (one of the power control
loop components) to the
antenna switch
.
GSM1800 and GSM 1900 TX path
The balanced TX signal from baseband is coming to the
Mjoelner RF ASIC
. The GSM1800
path of Mjoelner RF ASIC includes an common RF modulator for GSM1800 and
GSM1900. The BB signal is up-converted with the LO signal corresponding to the wanted
TX channel. The GSM1800/GSM1900 TX output of Mjoelner RF ASIC is a balanced signal.
From the balanced output of Mjoelner RF ASIC the signal is fed through the
TX balun
(T701) (balanced to single ended) and a 3dB pad to the GSM1800/1900 input of the
power amplifier (PA)
.
The GSM1800/GSM1900 part of the PA has a maximum output of app. 33dBm. The sup-
ply is coming directly from the battery terminals.
The output is controlled by the power control loop. From the output of the PA the signal
goes through the directional coupler (one of the power control loop components) to the
antenna switch
.
Antenna switch (TX/RX switch)
The antenna Switch works as a diplexer for the RX and TX signals. Moreover, it sup-
presses the TX harmonics generated by the PA. The antenna switch is controlled by the
Mjoelner RF ASIC using the control signals CONT1, CONT2 and CONT3.
The following table shows the possible different states.
General instructions for TX troubleshooting
Apply a RF cable to the test jig to allow the transmitted signal to act as normal. The RF
cable should be connected to the measurement equipment (GSM test equipment, power
meter, spectrum analyzer, or similar).
Be sure to use at least a 10dB attenuator, otherwise the results may be incorrect.
1 Connect PC with Phoenix to phone module
2 Provide the phone with power supply (3.6V).
3 Start Phoenix Service Software and open FBUS connection.
CONT1
[Volt]
CONT2
[Volt]
CONT3
[Volt]
EGSM RX
DCS RX
PCS RX
EGSM TX
DCS/PCS
TX
0
0
0
X
0
0
0
X
0
0
2.7
X
0
2.7
0
X
X
2.7
0
0
X