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Only for training and service purposes
3. TECHNICAL BRIEF
ͽͶͺΟΥΖΣΟΒΝΆΤΖΟΝΪ
3.2.2 GSM TRANSMITTER
The RTR6285 transmitter outputs(HB_RF_OUT1 and LB_RF_OUT1) include on-chip output matching inductors.
50ohm output impedance is achieved by adding a series capacitor at the output pins. The capacitor value may be
optimized for specific applications and PCB characteristics based on pass-band symmetry about the band center
frequency as shown in Figure 1-3.
[Figure 1-3] GSM Transmitter Outputs Topologies
The RTR6285 IC is able to support GSM 850/900 and GSM 1800/1900 mode transmitting. This design guideline
shows a tri-band GSM application. Both high-band and low band outputs are followed by resistive pads to ensure
that the load presented to the outputs remains close to 50ohm.
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