3. TECHNICAL BRIEF
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3.5.4 Thermistor (RT1000)
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 U8500.
3.5.5 UMTS transmit power detector (U1001)
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 U8500 uses National Semiconductor LMV225TLX power detector IC. In Figure 1.5.5-1, R1 is set
to 1.8kΩ resulting in an attenuation of 31.4dB. 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 LMV225TLX setup
as depicted in Figure1.5.5-1
Figure 3.5.5-1 Block diagram of LMV225TLX with high resistive tap
Summary of Contents for U8500
Page 1: ...Date February 2006 Issue 1 0 Service Manual Model U8500 Service Manual U8500 ...
Page 20: ...3 TECHNICAL BRIEF 21 ...
Page 32: ...3 TECHNICAL BRIEF 33 Figure 3 5 6 1 GSM PA functional block diagram ...
Page 35: ...3 TECHNICAL BRIEF 36 Figure 3 5 10 1 Bluetooth system architecture ...
Page 50: ...3 TECHNICAL BRIEF 51 Figure 3 10 3 2 1 PM6650 Functional Block Diagram ...
Page 114: ...4 TROUBLE SHOOTING 115 Loud Speaker U502 U503 Amp ...
Page 118: ...4 TROUBLE SHOOTING 119 C200 C201 for MIC serial capacitor ...
Page 121: ...4 TROUBLE SHOOTING 122 Q404 Q403 Q402 VBATT GND ...
Page 143: ...6 BLOCK DIAGRAM 144 6 3 Interface Diagram U8500 Interface Diagram ...
Page 145: ... 146 ...
Page 154: ... 155 U8500 8 PCB LAYOUT ...
Page 155: ... 156 8 PCB LAYOUT U8500 ...
Page 156: ... 157 8 PCB LAYOUT ...
Page 157: ... 158 8 PCB LAYOUT ...
Page 158: ... 159 U8500 8 PCB LAYOUT ...
Page 159: ... 160 U8500 8 PCB LAYOUT ...
Page 166: ...9 CALIBRATION 167 Click START button U8500 U8500_ver1 1 U8500 U8500 Click U8500 ...
Page 167: ... 168 ...
Page 169: ... 170 ...
Page 194: ...Note ...
Page 195: ...Note ...