User Guide

RH-26

2 - System Module CCS Technical Documentation

Page 38 ©Nokia Corporation Issue 1 02/04

This section presents the electrical specifications of the GSM850/GSM1800/GSM1900

triple band transceiver, RH-26. The section contains electrical specifications, functional

descriptions and block diagrams. The RF requirements follow ETSI GSM850/GSM1800/

GSM1900 phase2+ specifications.

The module is supporting GPRS, EGPRS, and HSCSD protocols. GPRS multislot class in 10

and HSCSD multislot class is 6. EGPRS multislot classes are 1 - 2. Power class in

EGSM850 mode is 4 (33 dBm output power) and 1 in 1800/1900 bands (30 dBm). In 8-

PSK (EDGE) -mode power class is E2 (27 dBm in 850 band, and 26 dBm in 1800 and 1900

bands). Multislot power class in EGSM850 is 5 and in GSM1800/1900 bands 1.

The operating temperature range for all the components is from -10 to +80 C° unless

otherwise mentioned in the specifications.

The RF module performs the necessary high frequency operations of the GSM850/

GSM1800/GSM1900 triple band engine. Both the transmitter and receiver have been

implemented by using direct conversion architecture.

Another core component is a power amplifier module which includes two amplifier

chains, one for GSM850 and the other for GSM1800/GSM1900. Other key components

are a 26 MHz VCTCXO (voltage controlled temperature compensated crystal oscillator)

for frequency reference, 3420-3980 MHz SHF VCO (super high frequency voltage con-

trolled oscillator), a front end module with a RX/TX switch with internal SAW filters

(EGSM850 and GSM1800), and one additional SAW filter and one balun for GSM1900

band. GSM850 and GSM1800 LNAs (low noise amplifier) for the receiver front-end are

integrated in Helgo, while GSM1900 LNA is external.

The control information for the RF is coming from the baseband section of the engine

through a serial bus, referred to later on as the 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 Helgo. Using the information obtained from the UPP, Helgo controls itself to the

required mode of operation and further sends control signals to the front end and 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.

The RF module takes care of all RF functions of the engine. RF circuitry is located on the

double side of the 8-layer PWB. PWB area for the RF circuitry is 8.7 cm

EMC leakage is prevented by using metal cans. The RF circuits are separated into three

blocks. The first includes the PA and TX 850band SAW. The second includes the front end

module, 1900 LNA and 1900 band SAW. The last block includes the Helgo RF IC, VCO,

VCTCXO and baluns. The RF transmission lines are made with striplines.

The RF transmission lines are made by striplines and microstriplines after PA.