LG U8210, Service Manual, Page: 20 / 231

3. TECHNICAL BRIEF
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3.2 GSM Mode
3.2.1 GSM Receiver
The Dual-mode U8210’s receiver functions are split between the three RFICs as follows:
• UMTS-2100 operation uses the RFL6200 LNA and RFR6200 Receiver ICs to implement the receive
signal path, accepting an RF input and delivering analog baseband outputs (I and Q).
• EGSM-900, DCS-1800, and PCS-1900 modes both use the RTR6250 IC only.
Each mode has independent front-end circuits and down-converters, but they share common
baseband circuits (with only one mode active at a time). All receiver control functions are beginning
with SBI 2 -controlled parameters.
RF Front end consists of antenna, antenna switch module(LMSP43MA-288), and three RX saw
filters(GSM, DCS, and PCS). The antenna switch module allows multiple operating bands and modes
to share the same antenna. In U8210, a common antenna connects to one of six paths: 1) UMTS-2100
Rx/Tx, 2) EGSM-900 Rx, 3) EGSM-900 Tx, 4) DCS-1800 Rx, and 5) DCS-1800,PCS-1900 Tx(High
Band Tx’s share the same path), 6) PCS-1900 Rx. UMTS operation requires simultaneous reception
and transmission, so the UMTS Rx/Tx connection is routed to a duplexer that separates receive and
transmit signals. EGSM, DCS, and PCS operation is time division duplexed, so only the receiver or
transmitter is active at any time and a frequency duplexer is not required.
2
The RFIC operating modes and circuit parameters are MSM-controlled through the proprietary 3-line Serial Bus Interface (SBI). The Application
Programming Interface (API) is used to implement SBI commands. The API is documented in AMSS Software - please see applicable AMSS
Software documentation for details.
ANT_SEL2 GPIO(11) ANT_SEL1 GPIO(10) ANT_SEL0 GPIO(9)
GSM 900 TX LOW LOW HIGH
GSM 900 RX/W-CDMA LOW LOW LOW
DCS 1800/PCS 1900 TX HIGH HIGH LOW
DCS 1800 RX LOW HIGH LOW
PCS 1900 RX HIGH LOW LOW
Table 3.2.1-1 Antenna Switch Module Control logic