3. TECHNICAL BRIEF
A. Power Amplifier Module
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Figure 3-3: Power Amplifier Module
Table 3-1: PAM Truth Table
The advanced quad-band Transmit Module designed for mobile handset applications
provides full RF transmit functionality.The GSM850/900 and DCS/PCS power amplifier
blocks including power control are combined with the low insertion loss quad-band
pHEMT switch, Tx harmonics filtering, integrated switch decoder, four receive ports,
and full ESD protection. This architecture eliminates the need for any PA-to-switch design
effort for phone designers. All four Rx ports are frequency independent and allow flexible
routing to the transceiver. Fabricated in high-reliability InGaP HBT / pHEMT technology, the
module supports GPRS class 12 operation and provides 50 Ohms input and output
impedances at all RF input and output ports. The module control inputs are CMOS
compatible and has no need for an external reference voltage. With its excellent efficiency
performance in all 4 bands, the power amplifier and switch module contributes to the overall
talktime targets of next generation mobile handset designs.
B. Quadrature Modulator
The Quadrature modulator takes the baseband I & Q signals and translates these into a GMSK
signal at the Transmit Intermediate Frequency (TX IF). After bandpass filtering and limiting the
TX IF signal is used as the reference input to the Phase Frequency Detector (PFD) of the
transmit PLL.
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