Receiver Description And Troubleshooting; Rx Signal Paths - Nokia RH-6 Series Rf Description & Troubleshooting

CCS Technical Documentation

Receiver Description and Troubleshooting

RX signal paths

The signal paths of the receiver are shown in following block diagram. Note that the pic-
ture shows EGSM900 receiver (upper left part), GSM1900 receiver (middle) and
GSM1800 receiver (lower).
SAW
INPL
RX RX900
INML
GSM
TX
RX SAW
INPH
PCS
RX1900
INMH
TX
PCN
SAW
INPM
RX
RX1800
INMM
VANTL / VANTM / VANTH
3
Antenna switch (RX/TX switch)
From the antenna-pad (J615) the RF signal is fed through the antenna low pass (C601,
L608, C602) to the antenna switch (Z601).
The antenna switch works as a diplexer. EGSM900 input signals pass to GSM_RX output.
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 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).
The antenna switch with routed lines has following typical insertion losses:
1.3dB@EGSM900, 1.6dB@GSM1800 and 1.6dB@GSM1900.
RX front-end
The RX front end includes three SAW filters (EGSM900 (Z604)GSM1800 (Z602),
GSM1900 (Z603)). Each of the SAW filters is matched with a differential matching cir-
cuit (LC-type) to the corresponding LNA input of Mjoelner RF ASIC (N601). The SAW fil-
ters provide out-of-band blocking immunity, the integrated LNAs provide the front-end
gains. Each of the SAW filters has a single-ended input and a balanced output which
provides a balanced RX signal to the corresponding input of the Mjoelner RF ASIC.
Issue 1 10/2003
Company Confidential
VR6
LNA
Bias
Pre-
LNA
gain
Pre-
LNA
gain
2 2
2
LNA
VDDDIG
1/2 1/4
RF
Controls
VDDRXBB
RF
Controls
Figure 8: RX signal paths
Copyright © 2003 Nokia Corporation.
Company Confidential
7 - RF Description & Troubleshooting
BBAMP
LPF1
BBAMP
LPF1
2
RH-6
Rx
supply
filter
BIQUA
D
DCN1 AGC
DCN2
LPF2
BIQUA
D
DCN1 AGC
DCN2
LPF2
Mjølner
Page 11
VRX
VR4
RXIP
RXIM
RXQP
RXQM
VDDLO