Transmitter Description And Troubleshooting; Tx Signal Paths - Nokia RH-6 Series Rf Description & Troubleshooting

CCS Technical Documentation

Transmitter Description and Troubleshooting

TX signal paths

For easy error tracking it is important to know the signal paths of the transmitter. The
components can be grouped into blocks and drawn as shown below.
Note that the picture shows both EGSM900 transmitter (bottom) and GSM1800/
GSM1900 transmitter (top).
GSM
Dir. Coupler
TX
PCN
TX
PCS
DET
VBATTRF
EGSM900 TX path
The balanced TX signal is provided by the baseband and is coming to the Mjoelner RF
ASIC. The TX paths of the Mjoelner RF ASIC include mainly two RF modulators for up-
conversion of the baseband signals, one for EGSM900 and one common for GSM1800/
GSM1900. The baseband signal is modulated with the LO signal corresponding to the
wanted TX channel. The GSM TX output of the Mjoelner RF ASIC is a balanced signal.
From the output of the Mjoelner RF ASIC the signal is fed through the EGSM TX SAW
filter (balanced to single ended), a 3dB pad, and the 900 MHz buffer to the EGSM input
of the power amplifier (PA).
The PA EGSM900 part has a maximum output power of app. 35dBm. Voltage supply is
coming directly from the battery connectors.
Issue 1 10/2003
Company Confidential
VANTL / VANTM / VANTH
3
VB_DET
VTXLOL
VTXLOH
VTXBH
VTXBL
PCN/PCS
OUTHP
Balun
OUTHM
PA
VTX
SAW
Buffer
OUTLP
OUTLM
EGSM
DET
PW-
PLFB1
loop
PLFB2
filter
VPCH/VPCL
PA_IDENT
Figure 9: Transmitter signal paths
Copyright © 2003 Nokia Corporation.
Company Confidential
7 - RF Description & Troubleshooting
VDDDIG
RF
Controls
VDDRXBB
RF
Controls
2
Open
collector
Open
collector
PWC
2
Supply
filter
VR2
TXP TXC
RH-6
1/2 1/4
2 2 2
Mjølner
2 2
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