LG L602i Service Manual page 29

3. TECHNICAL BRIEF
3.5.5 UMTS transmit power detector (U1008)
This detector couples PA output power level to calibrate the transmitter characteristic over the channel
variation and temperature. Its detector coupling range and converted voltage is based on diode
sensitivity and transmitter power level.
The L602i uses National Semiconductor LMV228TLX power detector IC. In Figure 1.5.5-1, Directional
coupler is 20dB. The output voltage is proportional to the logarithm of the input power. Figure1.5.5-2 shows
the output voltage versus PA output power of the LMV228TLX setup as depicted in Figure1.5.5-1
Figure 1.5.5-1 Block diagram of LMV228TLX Typical Application
Figure 1.5.5-2 Power detector response, Vout vs PA output power
- 30 -