Transmitter - LG 512W Service Manual

3. TECHNICAL BRIEF

3.3 Transmitter

The Transmitter part contains HD155128TF active parts and PAM, APC IC, coupler, FEM(front-end
module) circuit. The HD155128TF active part consists of a vector modulator and offset phase-
locked loop block(OPLL) including down-converter, phase detector, loop filter and dual band
transmit VCO which can operate at either final RF output frequency. The RF GMSK outputs from
the transmit VCO are fed directly to the RF power amplifiers. The peak output power and the profile
of the transmitted burst are controlled by means of a closed feedback loop. A dual band directional
coupler is used to sample the RF output from either PA. The PA outputs from the directional coupler
pass to the antenna connector via an integrated dual band front-end module.
Figure 3-5. Transmitter Block Diagram.
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