Antenna Switch (Rx/Tx Switch); Rx Front-End - Nokia RH-47 Series Rf Description And Troubleshooting

RH-47
7 - RF Description and Troubleshooting
SAW
RX850
RX
GSM
TX
RX RX1800
PCN
SAW
TX
RX1900
VANTL /
VANTM
2 2
VANTH

Antenna switch (RX/TX Switch)

Signal path of RF: From the antenna-pad (J800) the RF signal is fed through the antenna
low pass filter (C743, L610, C748) to the antenna switch (Z601).
The antenna switch has the function of a diplexer which consists of two paths for
GSM850 and GSM1900. The GSM850 input signals pass the switch to the GSM_RX out-
put. GSM1900 input signals pass to PCS_RX output. In receive mode both control signals
VC1 (VANTL) and VC2 (VANTH) have to be 0 V.
Signal paths:
GSM850: RX1-GSM output of the antenna switch
GSM1900: RX2-PCS output of the antenna switch
The antenna switch including routed lines has following typical insertion losses:
GSM850:
GSM1900:

RX front-end

The RX front-end includes two SAW filters for GSM850 (Z604) and GSM1900 (Z603).
They are matched to the corresponding LNA inputs of Mjoelner RF ASIC (N601) with dif-
ferential matching circuits (LC-type). The SAW filters 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.
The SAW filters have maximum insertion losses of:
GSM850:
GSM1900:
Page 24
Company Confidential
Figure 5: Rx signal paths
Rx
supply
filter
LNA
Bias
INPL
Pre-gain
LNA
INML
INPM
Pre-gain
LNA
INMM
2
2
INPH
LNA
INMH
VDDDIG
1/2
RF
Controls
VDDRXBB
RF
Controls
Copyright © 2004 Nokia Corporation
Company Confidential
BBAMP
LPF1
BBAMP
LPF1
2 2
1/4
GSM850 SAW filter (Z604).
GSM1900 SAW filter (Z603).
1.3dB
1.6dB
3.5dB
4.0dB
Nokia Customer Care
BIQUAD
DCN1 AGC
DCN2
LPF2
BIQUAD
DCN1 AGC
DCN2
LPF2
VDDLO
Mjølner
Issue 1 05/04
VRX
VR6
RXIP
RXIM
RXQP
RXQM