Issue 1 12/04
COMPANY CONFIDENTIAL
5
Copyright © 2004 Nokia. All Rights Reserved.
RAE-6/RA-4
7 - RF Description and Troubleshooting
Nokia Customer Care
CMT RF
■
Top-level description
The RF module performs the necessary high frequency operations of the GSM850/EGSM900/
1800/1900 tripleband (EDGE) engine. Both the transmitter and receiver have been implement-
ed by using direct conversion architecture which means that the modulator and demodulator
operate at the channel frequency.
The core of the RF is an application-specific integrated circuit, Honi. Another core component
is a power amplifier module which includes two amplifier chains, one for GSM850/EGSM900
and the other for GSM1800/GSM1900.
Other key components include
•
26 MHz VCTCXO for frequency reference
•
3296-3980 MHz SHF VCO (super high frequency voltage controlled oscillator)
•
Antenna switch module (ASM)
•
Three SAW filters
•
BAW-LNA module
The control information for the RF is coming from the baseband section of the engine through
a serial bus, referred later on as RFBus.
The whole RF circuitry is located on one side of the 8-layer PWB.
EMC leakage is prevented by using a metal shield with gasket. The RF circuits are separated
into two blocks.
•
PA, ASM, TK balun
•
Honi RF IC, VCO + balun, VCTCXO, BAW-LNA, Rx filter, Tx filter
The RF transmission lines constitute of striplines and microstriplines after PA.
