3. TECHNICAL BRIEF
3.2.1 GSM TRANSMITTER
The QTR8200/8600 transmitter outputs (TX_MB1 and TX_LB4) 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 3.2.4.
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[Figure 3.2.4] GSM Transmitter Outputs Topologies
The QTR8200/8600 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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