LG U300 Service Manual page 30

3. TECHNICAL BRIEF
3.5.4 Thermistor (RT100)
This thermistor senses temperature variations around UMTS PA to adjust PA gain deviation for assure
compliance with the applicable transmit power control standards. Negative temperature compensation
thermistor is used in the U300.
3.5.5 Dual band GSM power amplifier (U102)
The RF3166 is a high-power, high-efficiency power amplifier module with integrated power control that
provides over 50dB of control range. The device is a self-contained 6mmx6mm module with 50Ω input
and output terminals.
The device is designed for use as the final RF amplifier in GSM850, EGSM900, DCS and PCS
handheld digital cellular equipment and other applications in the 824MHz to 849MHz, 880MHz to
915MHz, 1710MHz to 1785MHz and 1850MHz to 1910MHz bands. The RF3166 incorporates RFMD's
latest VBATT tracking circuit, which monitors battery voltage and prevents the power control loop from
reaching saturation.
The VBATT tracking circuit eliminates the need to monitor battery voltage, thereby minimizing
switching transients. The RF3166 requires no external routing or external components, simplifying
layout and reducing board space.
Figure 3.5.5-1 GSM PA functional block diagram
- 31 -