User Guide

The filter is followed by an AGC amplifier with adjustable gain. The signal is further amplified before it is fed

to balanced analog IQ output pins. Analogue output pins are accompanied by reference voltage output, which

sets the DC level for the AD converter in BB ASIC.

Figure 108 WCDMA receiver after duplexer, LNA and SAW filter

GSM receiver

As GSM900, GSM1800 and GSM1900 RX branches are functionally identical, the following description is

applicable to all of them.

The received signal goes from the GSM antenna to the antenna switch module. The switch module contains

PIN diode switches for band and RX/TX. The antenna switch module is followed by integrated LNA stages in

the RF ASIC. The LNAs are followed by demodulators which downconvert the signal to baseband I and Q

signals.

In the BB-chain there are two adjustable gain stages and one mode specific gain. The first one called BB-gain

is just after the demodulator. It has a 12 dB gain range with 6dB steps. After the BB-gain there is the channel

select filter.

Main AGC amplifier proceeds the channel selection filter. It has 30 dB of gain control range with 3 dB steps.

Final amplifier stage is used as an output buffer for IQ signals. This stage is set to 0 dB gain in GSM mode.

Figure 109 GSM receiver after the antenna switch

Transmitter

Introduction to transmitter functionality

In RM-100, transmitter functions are implemented in the RF ASIC N7500.

RM-100

Nokia Customer Care System Module

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