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3. H/W CIRCUIT DESCRIPTION
3.3 Transmitter Part
The Transmitter part contains OPLL parts of RF Main Chipset [TRF6151, U607], Power Amplifier
Module [SKY77325, U604] and Front-End Module [ESHS-L080SF, FL601]. The transmit section of RF
Main Chipset [TRF6151C, U607] consists of an I/Q base-band up-converter, an offset phase-locked
loop [OPLL]. The RF GMSK outputs from the transmit VCO are fed directly to the RF power amplifier
modules.The peak output power and the profile of the transmitted burst are controlled by means of
incorporated power control circuits inside of PA and DAC output from the Baseband Controller. The PA
outputs pass to the antenna connector via Front-End Module [ESHS-L080SF, FL601].
I
Q
Serial
Interface
M DIV
XTAL
26 MHz
Tank
I
Q
3.3.1 IF Modulator
The Baseband Converter (BBC) within the Analog Baseband Chipset [TWL3014, U101] generates
I/Q baseband signals for the transmit vector modulator. The Tx-modulator implements a
quadrature modulator. A quadrature mixer up-converts the differential baseband I/Q signals with
the IFLO to generate a IF signal, which signal is filtered and used as the reference input to the
OPLL. The IFLO is divided by two to generate the quadrature LO signals for the quadrature
modulator.
90
Phase
Comp.
3.6 GHz
R DIV
Phase
Comp.
N DIVIDER
Figure 3. FEM Block diagram
- 16 -
GSM850 / GSM900
PAD
GSM1800 / GSM1900
PAD
Voltage
Regulators
PA
:2/:4
Controller
LNA850
/ LNA900
LNA1800
LNA1900
Quad Band PA
Quad Band
FEM
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