Interface Description EMII-1900 Service Manual Application Information
EMII-1900 V1.0 AnyDATA.NET Proprietary
Use Subject to Restrictions
2.3. Transmit End Bandpass Filter (F102, F103)
Transmit signals that have been converted from IF signals into RF signals after passing through the
RFT3100(U102) are inputted into the Power Amp (U103) after passing once again through RF BPF
(F101) in order to filter out noise signals amplified during the amplification of RF signals after going
through RFT3100(U102). This is carried out in order to create power level inputted to the Power AMP via
RF BPF (F101). IL of a RF BPF is 2dB as a maximum, whereas the ripple in the passing band is
2dB(maximum). The degree of the suppression of transmit signals on receive band is at least 20dB or
greater. The maximum power that can be inputted is about 25dBm.
2.4. Power Amplifier (U102)
The power amplifier U102 that can be used in the CDMA and FM mode has linear amplification
capability, whereas in the FM mode, it has a high efficiency. For higher efficiency, it is made up of one
MMIC (Monolithic Microwave Integrated Circuit) for which RF input terminal and internal interface
circuit are integrated onto one IC after going through the AlGaAs/GaAs HBT (heterojunction bipolar
transistor) process. The module of power amplifier is made up of an output end interface circuit including
this MMIC. The maximum power that can be inputted through the input terminal is +17dBm and
conversion gain is about 28dB. RF transmit signals that have been amplified through the power amplifier
are sent to the duplexer and then, sent out to the cell site through the antenna in order to prevent any
damages on circuits, that may be generated by output signals reflected from the duplexer and re-inputted
to the power amplifier output end.
2.5. Description of Frequency Synthesizer Circuit
2.5.1 Voltage Control Temperature Compensation Crystal Oscillator(TXC201, VCTCXO)
The temperature range that can be compensated by TCX201 which is the reference frequency generator of
mobile terminal is -30 ~ +80 degrees. TCX201 receives frequency tuning signals called TRK_LO_ADJ
from MSM as 0.5V~2.5V DC via R and C filters in order to generate the reference frequency of
19.68MHz and input it into the frequency synthesizer of UHF band. Frequency stability depending on
temperature is
⥮
2.0 ppm.
