LG KG270 Service Manual - Page 30

3. TECHNICAL BRIEF 3.9 RF Interface VC1 VC2 C417 C418 27p 27p FL400 LMSP2PAA-575TEMP 9 IN GSM1800_1900TX 1 6 3 7 GSM1800_1900RX VC_GSM850_900TX VC_GSM1800_1900TX 5 8 GND1 GND2 GSM850_900TX GSM850_900RX 2 4 10 GND3 Figure 3-9-1. ASM interface C419 3p 2 3 5 10 G1 G2 G3 G4 4 I2 O2_2 6 O2_1 7 O1_2 8 1 I1 O1_1 9 FL401 B9308 PART_NO SFSB0001401 IN CASE OF GSM850/PCS1900 CHANGE THIS DUAL SAW FILTER TO PART_NO SFSB0001301 L403 18nH C420 3p C421 3p C422 3p L404 5.1nH GSM_RXN GSM_RXP DCS_RXN DCS_RXP Figure 3-9-2. SAW Filter interface E-GOLDvoice features a fully integrated constant-gain direct conversion receiver, i.e. there is no interstage filter needed and the baseband level at the analogue IQinterface follows directly the RF input level. Depending on the baseband ADC dynamic range, single- or multiple-step gain switching schemes are possible. An integrated, selfaligning, low-pass filter ensures the receivers to function under blocking and reference interference conditions and avoids aliasing by baseband sampling. An automatic DC-offset compensation is implemented and can be switched depending on the gain setting. - 31 -