Rx Signal Paths - Nokia NEM-4 Series Troubleshooting Instructions

NEM-4
RF Troubleshooting

Rx Signal paths

The signal paths of the receiver are shown in following block diagram. Note that the pic-
ture shows EGSM900 (EGSM) receiver (top), GSM1900 (PCS) receiver (middle) and
GSM1800 (DCS/PCN) receiver (down).
SAW
INPL
RX RX900
INML
GSM
TX
Ant
Swi
RX
SAW
tch
INPH
PCS
RX1900
INMH
TX
PCN
SAW
INPM
RX
RX1800
INMM
VANTL / VANTM / VANTH
3
Antenna switch (RX/TX Switch)
From the antenna-pad (X600) the RF signal is fed through the antenna connector (X602)
to the RX/TX switch (Z601). The antenna connector represents a mechanical switch
between internal antenna and external antenna feed.
The RX/TX switch (Z601) works as diplexer. EGSM900 input signals pass to GSM_Rx out-
put. GSM1800 input signals pass to PCN_Rx output or PCS_Rx output, depending on the
control signal VANTH (Cont2).
From RX1-GSM output of the antenna switch the RX signal is routed in the inner layers
of the PWB to the EGSM900 SAW filter (Z604). From RX2-DCS output the GSM1800 RX
signal is routed to the GSM1800 SAW filter (Z602). From RX3-PCS output the RX
GSM1900 signal is routed to the GSM1900 SAW filter (Z603).
Page 6(b)-68
Company Confidential
VR6
VD
DR
XF
LNA
Bias
Pre-
LNA
gain
Pre-
LNA
gain
2 2
2
LNA
VDDDIG
1/2 1/4
RF
Controls
VDDRXBB
RF
Controls
Copyright  2003 Nokia Corporation
Company Confidential
CCS Technical Documentation
VD
DR
XB
B
BBAMP
LPF1
BBAMP
LPF1
2
Rx
supply
filter
BIQUA
D
DCN1 AGC
DCN2
LPF2
BIQUA
D
DCN1 AGC
DCN2
LPF2
Mjølner
Issue 1 09/2003
VRX
VR4
RXIP
RXIM
RXQP
RXQM
VDDLO