Issue 1 11/05
COMPANY CONFIDENTIAL
5
Copyright © 2005 Nokia. All Rights Reserved.
RA-8
7 - RF Description and Troubleshooting
Nokia Customer Care
CMT RF
■
Top-level description
The RF module performs the necessary high frequency operations of theEGSM900/1800/1900
tripleband (EDGE) engine. Both the 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 an application-specific integrated circuit, Honi. Another core component
is a power amplifier module which includes two amplifier chains, one for EGSM900 and the oth-
er 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.