Rf Module - Nokia NPM-6 Series Manual

System Module and User Interface

RF Module

The RF module comprises all RF functions of the NPM-6 engine. it is a triple band
EGSM900 / GSM1800 / GSM1900 transceiver
It is supporting GGSM1800PRS, EGPRS and HSCSD protocols and multislot classes 1 to 6.
Transmitter and receiver have been implemented by using direct conversion architecture
which means that the modulator and demodulator operate at the channel frequency.
The core of the RF is the Helga RF ASIC. Other main components include
- the power amplifier module which includes two amplifier chains, one for EGSM900 and
the other for GSM1800/GSM1900.
- 26 MHz VCTCXO for frequency reference,
- 3420-3980 MHz SHF VCO (super high frequency voltage controlled oscillator),
- front end module with a RX/TX switch and
two RF bandpass SAW filters inside, and three additional SAW filters. EGSM900 and
GSM1800 LNA's (low noise amplifier) for the receiver front-end are integrated in the
Helga while GSM1900 LNA is external.
The RF module includes metal shields for PA, the Helga and FM Radio.
Internal antenna is based on the PIFA concept (planar inverted F-antenna).
The RF is controlled by the baseband section of the engine through a serial bus, referred
later on as RFBus. This serial bus is used to pass the information about the frequency
band, mode of operation, and synthesizer channel for the RF. In addition, exact timing
information and receiver gain settings are transferred through the RFBus.
Physically, the bus is located between the baseband ASIC called UPP and the Helga.
Using the information obtained from UPP the Helga controls itself to the required mode
of operation and further sends control signals to the front end and power amplifier mod-
ules. In addition to the RFBus there are other interface signals for the power control loop
and VCTCXO control and for the modulated waveforms.
Page 38
ãNokia Corporation.
CCS Technical Documentation
Issue 1 01/03