Only For Training And Service Purposes - LG CT815 Service Manual

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 3-3.
The RTR6285 IC is able to support GSM 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.
Copyright © 2009 LG Electronics. Inc. All right reserved.

Only for training and service purposes

[Figure 3-3] GSM Transmitter Outputs Topologies
3. TECHNICAL BRIEF
- 19 -
LGE Internal Use Only