Nokia NEM-4 Series Troubleshooting Instructions page 73

CCS Technical Documentation
The RX/TX switch with routed lines has following typical insertion losses:
1.3dB@EGSM900, 1.6dB@GSM1800 and 1.6dB@GFSM1900.
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.
The SAW filters have maximum insertion losses of
3.5dB@EGSM900, 4.0dB@GSM1800 and 4.0dB@GSM1900.
RX paths of Mjoelner RF ASIC
The balanced RX signal is amplified by the integrated LNA and the subsequent Pre-Gain
stage. After amplification the RX signal is down-converted with a LO signal coming from
the local oscillator.
The RX paths of Mjoelner RF ASIC consist of following building blocks:
• Separate LNAs for each of the three bands: EGSM900, GSM1800 and GSM1900.
• Two PREGAIN amplifiers, one for EGSM900 and one common for GSM1800 and
GSM1900.
• Two passive I/Q mixers (MIX), one for EGSM900 and one common for GSM1800 and
GSM1900.
Issue 1 09/2003
Company Confidential
Figure 11: Antenna switch Rx test points
Copyright  2003 Nokia Corporation
Company Confidential
NEM-4
RF Troubleshooting
Page 6(b)-69