Gsm Mode - LG -E730 Service Manual

3. TECHNICAL BRIEF

3.2 GSM mode

3.2.1GSM RECEIVER
The GSM-850, GSM-900, GSM-1800, and GSM-1900 receiver inputs of QTR8200/8600 are connected directly to
the transceiver front-end Module. Since the GSM-850 band covers the same frequency range as the CDMA
cellular band and the UMTS-850 band. Sharing the GSM front-end with a CDMA or UMTS path is called co-
banding.
GSM-850, GSM-900, GSM-1800, and GSM-1900 receiver inputs use differential configurations to improve
common-mode rejection and second-order non-linearity performance. For example Figure 3.2.1 shows receiver
input topologies for GSM850 and GSM900 (DCS/PCS have the same receiver input topologies). The balance
between the complementary signals is critical and must be maintained from the RF filter outputs all the way into
the IC pins.
[Figure 3.2.1] GSM900, DCS/PCS Receiver Inputs Topologies
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