LG L705ix Service Manual page 15

3. TECHNICAL BRIEF
that translate the signal directly from RF-to-baseband using radioOne ZIF techniques. The high-band
UMTS receive path and low-band path are accommodated in the RTR6275 IC. The RFIC.s Rx analog
baseband outputs, for the receive chains, connect to the MSM IC.
For the transmit chains, the RTR6275 IC directly translates the Tx baseband signals (from theMSM
device) to an RF signal using an internal LO generated by integrated on-chip PLL and VCO. The
RTR6275 IC outputs deliver fairly high-level RF signals that are first filtered by Tx SAWs and then
amplified by their respective UMTS PAs. The high- and low-band UMTS RF transmit signals emerge
from the RTR6275 transceiver.
ISDB-T 1seg receive path include an LNA, Mixer, IF Part and OFDM demodulator which are
accommodated in ENT34606 IC.
L705iX power supply voltages are managed and regulated by the PM6650 Power Management IC.
This versatile device integrates all wireless handset power management, general housekeeping, and
user interface support functions into a single mixed signal IC. It monitors and controls the external
power source and coordinates battery recharging while maintaining the handset supply voltages using
low dropout, programmable regulators.
The device's general housekeeping functions include an ADC and analog multiplexer circuit for
monitoring on-chip voltage sources, charging status, and current flow, as well as user-defined off-chip
variables such as temperature, RF output power, and battery ID. Various oscillator, clock, and counter
circuits support IC and higher-level handset functions. Key parameters such as under-voltage lockout
and crystal oscillator signal presence are monitored to protect against detrimental conditions.
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