User Guide

Issue 1 12/04 COMPANY CONFIDENTIAL 5

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.