Panasonic EB-G60 Service Manual

Also see for EBG60 - CELL PHONE: Operating instructions Operating instructions

– 5–11 –5.3.3. Functional DescriptionRx-VCOUHF-VCO(LO)Ö . ÖVCTCXO13MHzFrefLECLKDataRxqnRxqpAFCTransceiverCX74017Dual-bandTR switchVC1 VC2 VC3RxinRxipRxqnRxqpPCO1PCO2TXENARXENASXENAU100U106 U111ANTGSMSAWDCSSAWRxinRxipDCOCDCOCF101 SAW FilterFig 5.4. : Receiving BlockingThe main building block, illustrating as Fig 5.1 receive path, for the Dual Band receiver is the CX74017 transceiver IC(U100) which includes a direct conversion receiver with I and Q quadrature demodulation. Received signals from theantenna are passed to the dual band antenna switch module U111. This module contains a diplexer which filters thesignal to the required receiver path (E-GSM 900 or GSM 1800). Pin diode switches within U111 route the signal pathfrom the transmitter or to the receiver as required. Output signals from U111 are then applied via the dual band SAWfilter FL101 to the balanced Low Noise Amplifiers (LNA) onboard U100.Output from the LNAs are applied to the bufferamplifiers and a pair of Gilbert Cell mixers within U100. The mixers convert the incoming signals directly down tobaseband frequencies. The I, Q local oscillator signals for the mixers is derived from a 925M-1880M Hz RFLO, diveddown by high speed converter. The receiver has two separate front-end blocks, optimized for 900 MHz and 1800 MHzrespectively.The front-end gain is programmed as follows:These settings allow the signal in the receiver to be optimized, particularly under high signal level conditions. Front-Endgain is programmed by 3-wire bus signal from the baseband.The mixer stage is followed by the I, Q baseband low-pass filters and programmable gain amplifiers (PGA). Each three-stage VGA is DC-coupled and has a 100 dB control range in 2 dB steps.■ GSM 1900Uplink frequencies for the GSM 1900 band (512 = ARFCN = 810) can be calculated as follows:Uplink frequency = 1930 MHz + ((ARFCN - 511) x 0.2 MHz) e.g. for CH6801930 MHz + ((185 - 511) x 0. 2MHz)= 1930 MHz + (33.8 MHz)= 1963.8 MHz