Receiver Path - LG GX300 Service Manual

3. TECHNICAL BRIEF
3.8.1 Transmitter path
This module features a fully integrated zero IF transmitter. The baseband transmitted data Is
digitally modulated in the modem block and up-converted the 2.4GHz ISM band in the Transmitter
path. The transmitter path consists of signal filtering, I/Q up-conversion, high -output power
amplifier(PA), and RF filtering. It also incorporates modulation schemes P/4-DQPSK for 2 Mbps and
8-DPSK for 3 Mbps to support enhanced data rate.
• Digital modulator
The digital modulator performs the data modulation and filtering required for the GFSK, B/4DQPSK,
and 8-DPSK signal. The fully digital modulator minimizes any frequency drift or anomalies in the
modulation characteristics of the transmitted signal and is much more Stable than direct VCO
modulation schemes.
• Power Amplifier
The integrated PA for the BCM2070 is configurable for Class 2 operation, transmitting up to +4 dBm
as well as Class 1 operation and transmit power up to +12 dBm at the chip, GFSK, >2.5V supply.
Due to the linear nature of the PA, combined with some integrated filtering, no External filters are
requires for meeting Bluetooth and regulatory harmonic and spurious requirements. For integrated
mobile handset applications, where Bluetooth is integrated next to the celluar radio, minimal
external filtering can be applied to achieve near thermal noise levels for spurious and radiated
noise emissions.
Using a highly linearized, temperature compensated design the PA can transmit +12 dBm for Basic
rate and +10 dBm for enhanced data rates(2 to 3 Mbps). A flexible supply voltage range Allows the
PA to operate from 1.2V to 3.0V. The minimum supply voltage at VDDTF is 1.8V to achieve +10dBm
of transmit power.

3.8.2 Receiver path

The receiver path uses a low IF scheme to down-convert the received signal for demodulation in
the digital demodulator and bit synchronizer. The receiver path provides a high degree of Linearity,
an extended dynamic range, and high order on-chip channel filtering to ensure reliable operation
in the noisy 2.4GHz ISM bnad. The front-end topology, with built-in out -of-bnad attenuation,
enables the device to be used in most applications with no off-chip Filtering. For integrated
handset operation where the Bluetooth function is integrated close to the celluar transmitter,
minimal external filtering is required to eliminate the desensitization of The receiver by the cellular
transmit signal.
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3. TECHNICAL BRIEF
Only for training and service purposes