General Description Of The Rf Circuits; Receiver Signal Path - Nokia RH-18 Manual

CCS Technical Documentation

General description of the RF circuits

In the following general descriptions different colours are used in the block diagram. The
GSM 850 signal route is shown in red, the GSM1900 route in green and the common sig-
nal lines are shown in blue. Signal lines which is common for both

Receiver signal path

The signal from the antenna pad is routed to the RX/TX switch (Z700). If no control volt-
age is present at VANT2 and VANT1 the switch works as a diplexer and the GSM850 sig-
nal is passed through the RX/TX switch to GSM-RX and the GSM1900 signal is passed to
DCS-RX.
From the RX/TX switch the GSM850 signal is routed to the SAW filter (Z602). The pur-
pose of the SAW filter is to provide out-of band blocking immunity and to provide the
LNA in Mjoelner (N600) with a balanced signal. The front end of Mjoelner is divided into
a LNA and Pre-Gain amplifier before the mixers.
The output from the mixer is feed to Baseband part of Mjoelner where the signals ampli-
fied in the BBAMP and low pass filtered in LPF1 before the DC compensation circuits in
DCN1. The DCN1 output is followed by a controlled attenuator and a second lowpass fil-
ter LPF2. The output from LPF2 is DC centered in DCN2 before being feed to the BB for
demodulation.
The GSM1900 signal chain is similar to GSM850, the SAW filter numbered Z601.
Issue 1 10/03
Company confidential
Figure 14: Receiver signal path
Nokia Corporation.
RH-18/36/38
Engine module
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