LG U8210, Service Manual, Page: 18 / 231

3. TECHNICAL BRIEF
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A generic, high-level functional block diagram of U8210 is shown in Figure 3.1-1.
One antenna collects base station forward link signals and radiates handset reverse link signals. The
antenna connects with receive and transmit paths through a switch module (plus a duplexer for UMTS-
2100 operation).
The UMTS receive signal is amplified by the RFL6200 LNA then passes through a bandpass filter
before being applied to the RFR6200 Receiver IC. On-chip circuits downconvert the received signal
directly from RF to baseband using radioOne Zero-IF techniques. Generation of the UMTS
downconverter LO is distributed between the RTR6250 (phase-locked loop), the RFR6200 (buffer
amplifiers and LO distribution circuits) and external UHF VCO and loop filter circuits. The RFR6200 IC
outputs analog baseband signals for further processing by the MSM device. This baseband interface is
shared with the RTR6250 EGSM /DCS/PCS receiver outputs.
EGSM, DCS and PCS receive signals pass through their bandpass filters then are applied to the
RTR6250 IC. Similar to the UMTS path, RTR6250 circuits downconvert the received signals directly
from RF to baseband. The EGSM/DCS/PCS downconverter LO is generated mostly within the
RTR6250 (PLL and distribution functions); the UMTS Rx CH VCO and loop filter are off-chip. The RTR
analog baseband outputs are routed to the MSM6250 IC for further processing (an interface shared
with the RFR).
The UMTS transmit path begins with analog baseband signals from the MSM device that drive the
RTR6250 IC. Integrated PLL and VCO circuits generate the Tx LO used in the quadrature upconverter
that translates baseband signals directly to RF. The RTR6250 output driver stages deliver fairly high-
level signals that are filtered and applied to the power amplifiers (PA). The PA output is routed to the
antenna through a duplexer and switch module.
The shared EGSM-900, DCS-1800, and PCS-1900 transmit path begins with the same baseband
interface from the MSM6250 IC that is used for the UMTS band. A single EGSM/DCS/PCS quadrature
upconverter translates the GMSK-modulated signal to a convenient intermediate frequency (IF) that
forms one input to an offset phase-locked loop (OPLL). OPLL functions are split between the
RTR6250 IC and off-chip loop filter and dual Tx VCO circuits, and translate the GMSK-modulated
signal to the desired EGSM-900, DCS-1800 or PCS-1900 channel frequency. This signal is applied to
a dual power amplifier (only one is active at a time). The enabled path continues with the PA, an
automated power control (APC) circuit that samples the transmit power and adjusts its level, the switch
module (which includes a band-appropriate lowpass filter), and the antenna.
U8210 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.