Only For Training And Service Purposes - LG TU550 Service Manual

3.5.11 UMTS Rx VCO (X100 : MQW541A1G44)
The UMTS dual-band Rx VCO is a key component in PLL2; VCO performance directly impacts Polar
calibration accuracy and UMTS receiver performance. When the phone is not in the UMTS mode the
unused VCO must be turned off by UHF_VCO_EN signal from MSM6275. Using only the external
UMTS_RX_VCO signal, the LO generation and distribution circuits create the necessary LO signals for
the quadrature down-converter.
Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

3. TECHNICAL BRIEF
- 33 -
LGE Internal Use Only