LG -A290 Service Manual page 37

MCU Subsystem

The MCU (Micro-Controller Unit) subsystem contains the 3-bit RISC microprocessor, internal memory and the ROM
patch function. It also contains the UART interface controller and the power/clock management function.
Bluetooth Subsystem

The Bluetooth subsystem contains the Bluetooth baseband subsystem and the Bluetooth RF subsystem.
The Bluetooth baseband subsystem contains a baseband processor which supports timing control, bit-stream
processing, encryption, frequency hopping, and modulation/demodulation. It also contains the audio codec, Wi-Fi
coexistence interface controller, and a sleep mode controller.
The Bluetooth RF subsystem contains a fully integrated transceiver. For TX path, the baseband transmit data is digitally
modulated in the baseband processor, then up-converted to .4GHz RF channels through DA converter, filter, IQ up-
converter, and the power amplifier. The power amplifier is capable of transmitting 10dBm power for class-1.5 operation.
For RX path, MT666 is a low IF receiver architecture. An image-reject mixer down-converts the RF signal to the IF with
the LO from the synthesizer, which could support different clock frequencies as the reference clock as described in
section 4.. The mixer output is then converted to digital signal, down-converted to baseband for demodulation. A fast
AGC enables the effective discovery of device within the dynamic range of the receiver.
MT666 features self calibration schemes to compensate the process and temperature variation to maintain high
performance. Those calibrations are performed automatically right after system boot-up.
FM Subsystem

MT666's FM radio subsystem provides a completely integrated FM RX receiver supporting 76-108 MHz FM bands with
50KHz tuning step. It also performs fast channel seek/scan algorithm to validate 00 carrier frequencies in 6 seconds. In
addition to receive FM audio broadcasting, the digital RDS/RBDS data system is supported as well. The integrated FM
transceiver utilizes state-of-the-art digital demodulation/modulation techniques to achieve excellent performance.
In order to achieve high SINAD, good sensitivity and excellent noise suppression, the FM receiver adopts adaptive
demodulation scheme to optimize RX system performance in all range of signal quality by reference of a very
sophisticated channel quality indicator (CQI). When the received signal quality is poor, the design not only enhances the
ACI rejection capability but also uses a very ingenious skill to soft mute annoying noise so as to provide good perception
quality.
The FM subsystem requires only the availability of the 3.768KHz clock input, and can be operated completed
independently from the Bluetooth subsystem. Therefore, allowing for full simultaneous operation and coexistence with
the Bluetooth subsystem while maintaining the most power-efficient consumption under different operating states.
The FM subsystem supports high performance stereo analog line out. In WLCSP package, it also supports digital audio
out.
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3. TECHNICAL BRIEF
Only for training and service purposes