User Guide

NPE-4
6 - Troubleshooting PAMS Technical Documentation
Page 6-38 ãNokia Corporation. Original
Path of the transmitted EGSM signal
For easy error tracing it is important to know the signal path of the EGSM transmitter.
The components can be grouped into blocks and drawn as shown below. Note that the
picture shows both EGSM transmitter (bottom) and PCN transmitter (top).
Hagar
The Balanced TX signal from baseband is coming to the RF IC Hagar. It includes RF mod-
ulators, one for EGSM and one for PCN. The Baseband signal is mixed with the LO signal
corresponding to the wanted TX channel. The PCN TX output of Hagar is a balanced sig-
nal.
From the output of Hagar the signal goes through the EGSM TX SAW filter (Balanced to
single ended) to the PA EGSM input.
PA
The PA EGSM part has a maximum output at app. 35dBm. The supply is coming directly
from the Battery terminals.
The output is controlled by Hagar by the power control loop. From the ouput of the PA
the signal goes through the directional coupler (one of the power control loop compo-
nents) to the RXTX Switch.
RXTX Switch
The RXTX Switch is making the filtering between RX and TX Bands and between EGSM
and PCN bands. It is controlled by Hagar by the two voltages VANT1 and VANT2. The fol-
lowing table shows the different states.
VANT1 [Volt] VANT2 [Volt] EGSM Rx PCN Rx EGSM Tx PCN Tx
0 0 X X
0 2.7 X
2.7 0 X
TXI_0/TXI_180
DET
Ant Switch
RX
RX
TX
TX
OUTP_P_TX/
OUTM_P_TX
OUTP_G_TX/
OUTM_G_TX
2
2
TXQ_0/TXQ_180
2
2
Open collector
Open collector
GSM
PCN
VBATTRF
PWC
DET
TXP TXC
Vpctrl_g Vpctrl_p
RF
Controls
VBD
V_ANT_1/
V_ANT_2
2
PA
Dir. Coupler
TXC
TXP
VBATTRF
TXIOUTP/TXIOUTN
VR2
VTX_B_P
VTX_B_G
Antenna connector
TXQOUTP/TXQOUTN
VTXLO_G
2
2
BALUN
SAW
HAGAR