Siemens A55 Repair Documentation

Also see for A52: User guide

V 1.10 Page 10of 45 ICM MP CCQ GRMA52/A55/C55 IFX Company Confidential © Copyright Siemens AG 08/034.4 Antenna Switch / External Antenna Connector(electrical/mechanical only C55)The mechanical antenna switch for the differentiation between the internal and externalantenna.4.5 Frontendmodul (Electrical Antenna Switch)EGSM900/GSM1800 <> Receiver/TransmitterThe frontend has two functions.- to select the different GSM bands- to switch between RX and TX modeInside the frontendmodul SAW filters are integrated in the RX paths.For dual band mode the FEM needs two supply voltages (VC1, VC2) that are directlyprovided by the Smarti DC (FEM1 and FEM2). The following logical table shows thedifferent modes of the FEM.Mode Selection Vc. 1 Vc.2 Vc.3EGSM900 RX LOW LOW LOWEGSM900 TX HIGH LOW LOWGSM1800 RX LOW LOW LOWGSM1800 TX LOW HIGH LOWGSM1900 RX LOW LOW HIGHGSM1900 TX LOW HIGH LOWTwo balanced SAW filters are integrated to have good stop-band attenuation in the GSMand the PCN RX paths.Top ViewBlock diagramto / fromdiplexerExternal Internal