LG LG-P500, Руководство по обслуживанию

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Only for training and service purposes LGE Internal Use Only
3. TECHNICAL BRIEF
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A generic, high-level functional block diagram of LGP500 is shown in Figure 1-1. One antenna collects base
station forward link signals and radiates handset reverse link signals. The antenna connects with receive and
transmit paths through a ASM(Antenna-Switch-Module).
The UMTS receive paths each include an LNA, an RF band-pass filter, and a downconverter that translate the
signal directly from RF-to-baseband using radioOne ZIF techniques. The RFIC’s Rx analog baseband outputs,
for the receive chains, connect to the MSM IC. The UMTS and GSM Rx baseband outputs share the same
inputs to the MSM IC.
For the transmit chains, the RTR6285 IC directly translates the Tx baseband signals (from the MSM device) to
an RF signal using an internal LO generated by integrated onchip PLL and VCO. The RTR6285 IC outputs
deliver fairly high-level RF signals that are first filtered by Tx SAWs and then amplified by their respective
UMTS PAs. In the GSM receive path, the received RF signals are applied through their band-pass filters and
down-converted directly to baseband in the RTR6285 transceiver IC. These baseband outputs are shared with
the UMTS receiver and routed to the MSM IC for
further signal processing.
The GSM/EDGE transmit path employs one stage of up-conversion and, in order to improve efficiency, is
divided into phase and amplitude components to produce an open-loop Polar topology:
1. The on-chip quadrature up-converter translates the GMSK-modulated signal or 8-PSK modulated signal, to
a constant envelope phase signal at RF;
2. The amplitude-modulated (AM) component is applied to the ramping control pin of Polar power amplifier
from a DAC within the MSM LGP500 power supply voltages are managed and regulated by the PM7540
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.