Nokia 2630 RM-298 Service Manual

Contents

Nokia 2630 RM-298 Service Manual Manual pdf 167 page image

Table 16 Frequency bands and TX power classSystem Frequency band TX power classGSM900 Tx: 880 – 915 MHz 4 (33dBm)Rx: 925 – 960 MHzGSM1800 Tx: 1710 – 1785 MHz 1 (30dBm)Rx: 1805 – 1880 MHzTable 17 Multi-slot classMultislot ClassGPRS MSC 10 (4Dn/2Up), sum=5E-GPRS MSC 6 in DL, max. 3DnTransmitter - general descriptionThe transmitter has separate, parallel paths covering the different bands. The transmitter operates in GMSKmode only. The power level control circuitry is integrated in the front-end module.Each path of the transmitter is composed of a baseband lowpass filter for the I/Q signals and a quadraturedirect modulator integrated in PMB3258. At the modulator’s output there is a bandpass filter for each band(so-called H3 filter) and a balun transformer to convert the differential output signal from the modulator intoa single-ended 50 ohm signal. This signal is fed into the input of the PA. The two power amplifiers and theantenna switch are integrated in a single module with built-in power control loop.The two control methods used are open-loop Vcc control (RFMD) and feedback control with current sensing.The reference waveform (TXC) for the control loop comes from the baseband. The output of the PA goes intoa low pass filter located inside the FEM (Front End Module). Finally the transmit signal goes through the bandselection and TX/RX switches to the antenna port.The FEM is controlled with four digital control signals (TXP, Vc1, Vc2 and Vc3) to meet the TDMA frame timingrequirements.Transmitter - signal processingThe I/Q signals coming from the baseband section are fed into the modulator and converted up to the carrierfrequency. The I/Q are post filtered by a 1st order passive RC filter (discrete components on PWB) and a 3rdorder active filter (Legendre type) inside PMB3258.The nominal output level of the modulator is +3.5 dBm in both bands. The modulator's output is an open-collector type and need an external load and a DC supply feed. The load and the DC supply feed areimplemented as the part of the H3 filter.The filtered signal is fed into the input of the FEM, which amplifies it to the desired power level and providesthe signal at the antenna port.There is also a temperature sensor close to the FEM to enable SW temperature compensation for e.g. thepower levels. The sensor is connected to one of the slow ADC channels in the baseband.Receiver - general descriptionThe receiver is a direct conversion linear receiver. It is a dual-band receiver with receiver paths for eitherGSM850/1900 or GSM900/1800 configuration.RM-298; RM-299System ModuleIssue 1 COMPANY CONFIDENTIAL Page 6 –21Copyright © 2007 Nokia. All rights reserved.