Nokia 6020b Service Manual
RM-31
Nokia Customer Care
7 - System Module
44
COMPANY CONFIDENTIAL
Issue 1 03/2005
Copyright © 2005 Nokia. All Rights Reserved.
RF Module Description
The RF module performs the necessary high frequency operations of the triple-band engine.
Both the transmitter and receiver have been implemented by using a direct conversion archi-
tecture, which means that the modulator and demodulator operate on the channel frequency.
No intermediate frequencies are used for up- or down-conversion.
Both the transmitter and receiver have been implemented by using a direct conversion archi-
tecture, which means that the modulator and demodulator operate on the channel frequency.
No intermediate frequencies are used for up- or down-conversion.
The core of the RF is an application-specific integrated circuit (RF ASIC), Helgo86. The other
RF key components are:
RF key components are:
• An EDGE capable power amplifier module, which includes two amplifier chains,
one for the low band (GSM850) and the other for both high bands (GSM1800 and
GSM1900).
one for the low band (GSM850) and the other for both high bands (GSM1800 and
GSM1900).
• An antenna switch module, which contains filters and switches to combine the two
TX-PA outputs and three Rx chain inputs to the antenna port.
TX-PA outputs and three Rx chain inputs to the antenna port.
• 26 MHz reference oscillator (VCTCXO).
• 3296-3980 MHz VCO.
• Three SAW filters for Rx band filtering.
• One SAW filter for the low band (GSM850) Tx path.
The control information for the RF is coming from the baseband section of the engine through
a serial bus, referred later on as RFBus. This serial bus is used to pass the information on the
frequency band, mode of operation, and synthesizer channel for the RF. In addition, exact tim-
ing information and receiver gain settings are transferred through the RFBus.
a serial bus, referred later on as RFBus. This serial bus is used to pass the information on the
frequency band, mode of operation, and synthesizer channel for the RF. In addition, exact tim-
ing information and receiver gain settings are transferred through the RFBus.
Physically, the bus is located between the baseband ASIC called UPP and the RF ASIC. Using
the information obtained from UPP, the RF ASIC controls itself to the required mode of opera-
tion and further sends control signals to the antenna switch and the power amplifier modules.
the information obtained from UPP, the RF ASIC controls itself to the required mode of opera-
tion and further sends control signals to the antenna switch and the power amplifier modules.
In addition to the RFBus, there are still other interface signals for the power control loop and
VCTCXO control and for the modulated waveforms (IQ signals).
VCTCXO control and for the modulated waveforms (IQ signals).
The RF circuitry is located in two shielding chambers on one side of the 8 layer PWB containing
the following key components: The Small Signal Chamber contains RF ASIC, reference oscil-
lator (VCTCXO), VCO, and Rx/Tx SAW-filters (GSM850/GSM1800). The Large Signal Cham-
ber contains the RF Power Amplifier, the Antenna Switch Module, and the Rx SAW-filter and
LNA (GSM1900).
the following key components: The Small Signal Chamber contains RF ASIC, reference oscil-
lator (VCTCXO), VCO, and Rx/Tx SAW-filters (GSM850/GSM1800). The Large Signal Cham-
ber contains the RF Power Amplifier, the Antenna Switch Module, and the Rx SAW-filter and
LNA (GSM1900).