LG L602i Service Manual page 23

3. TECHNICAL BRIEF
The RFR6202 IC includes LO generation and distribution circuitry to reduce off-chip component
requirements. The UMTS RX LO source is created using an external UMTS_RX_VCO that is closed-
loop controlled by the RTR6250 PLL2 via a discrete loop filter, with an RFR6202 buffer amplifier
supplying the PLL feedback signal. When the phone is not in the UMTS800 or UMTS2100 mode the
unused VCO must be turned off by UHF_VCO_0_EN logic signal from MSM6250. Using only the
external UMTS_RX_VCO signal, the LO generation and distribution circuits create the necessary LO
signals for the quadrature downconverter. By definition, the Zero-IF downconverter requires F equal to
LO
F , and the RFR6202 design achieves this without allowing F to equal F .
RF VCO RF
Figure 1.3.1-2 RFR6202 IC functional block diagram
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