LG Electronics Inc.
LG501C
CHAPTER 3. Circuit Description
1. RF Transmit/Receive Part
1.1 Overview
The Tx and Rx part employs the Direct Conversion system. The Tx and Rx frequencies are respectively
824.04~848.97MHz and 869.04~893.97MHz for cellular and 1850~1910MHz and 1930~1990MHz for
PCS .The block diagram is shown in [Figure 1-1]. RF signals received through the antenna are seperated
by quadplexer. RF Signal fed into the low noise amplifier (in QSC6055) through the quadplexer. Then, they
are combined with the signals of local oscillator (VCO) at the down conversion mixer (in QSC6055) in
order to create Base-band frequency. Then, this signal is changed into digital signal by the analog to digital
converter (ADC, A/D Converter), and the digital circuit part of the QSC (Qualcomm Single Chip) 6055
processes the data from ADC. The digital processing part is a demodulator.
In the case of transmission, RF transmitter (in QSC6055) receives QPSK-modulated analog signal from
the QSC6055. In QSC6055, the baseband quadrature signals are upconverted to the Cellular or PCS
frequency bands and amplified to provide signal drive capability to the power amp.
After that, the RF signal is amplified by the Power Amp in order to have enough power for radiation. Finally,
the RF signal is sent out to the cell site via the antenna after going through the coupler and quadplexer.
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Summary of Contents for 501C
Page 1: ...Internal Use Only Service Manual LG 501C Date January 2011 Issue 1 0 ...
Page 21: ...LG Electronics Inc LG501C X XYUGj GutzpkG G GvrU XXUGj GtjjG G Gvr XWUGj G Gz Gj G G GvrU 21 ...
Page 25: ...LG Electronics Inc LG501C Y YZUGw GvrU Y UGw GvrU YYUGw GvrU 25 ...
Page 28: ...LG Electronics Inc LG501C Figure 1 1 Block Diagram of LG501C 28 ...
Page 30: ...LG Electronics Inc LG501C 30 ...
Page 31: ...LG Electronics Inc LG501C 31 ...
Page 50: ...LG Electronics Inc LG501C Waveform U1801 2pin U1102 5pin U1102 1pin 50 ...
Page 59: ...LG Electronics Inc LG501C Waveform 4 1 2 c 4 1 2 d U1801 2pin U1102 5pin U1102 2pin 59 ...
Page 133: ...LG Electronics Inc LG501C Appendix 133 ...
Page 134: ...LG Electronics Inc LG501C Appendix 1 Block Diagram LG501C BLOCK DIAGRAM 134 ...
Page 135: ...LG Electronics Inc LG501C Appendix 2 Circuit diagram 135 ...
Page 147: ...LG Electronics Inc LG501C 2 1 MAIN PCB CIRCUIT DIAGRAM Internal Use Only 147 ...
Page 150: ...LG Electronics Inc LG501C Appendix 3 BGA Pin Map 150 ...
Page 151: ...LG Electronics Inc LG501C 3 1 U7301B BCM2070B2KUBXG EUSY0418701 USED PIN NOT USED PIN 151 ...
Page 152: ...LG Electronics Inc LG501C 3 2 U2101B QSC6055 CD EUSY0336202 NOT USED PIN 152 ...
Page 153: ...LG Electronics Inc LG501C 3 3 U2201B H8BCS0SI0BAR 46M EUSY0347506 153 ...
Page 154: ...LG Electronics Inc LG501C 3 4 U6481B TPA6136A2YFF EUSY0412501 USED PIN NOT USED PIN 154 ...
Page 155: ...LG Electronics Inc LG501C Appendix 4 Component Layout 155 ...