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Power Amplifier And Antenna Switch - Siemens A35 Repair Documentation

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4.5.2 Transmitter : Power Amplifer Amplifier and Antenna Switch
Splited by a discrete circuit into EGSM900 and GSM1800, the TXVCO output signal
arrives at the power amplifier. The dual band power amplifier module (Z502)
is assembled on a ceramic substrate in one housing. The module amplifies the
output signal of the TXVCO to the required PCL (controlled by the feedback circuit
according to settings from the logic) .The different amplifiers are switched on by
TXONPCN/TXONGSM via the transistor (V508). The signal
the operation point setting of low GSM PCLs. The power amplifier is supplied directly
from the battery (BATT+).
After amplification the signal passes on the way to the antenna the diplexer (Z503).
A part of the TX output signal is decoupled via a directional coupler (realised by
conductive tracks), is equalised and temperature compensated by a detector
diode (V505).
This so gained voltage, is compared through an operation amplifier (N501) with the
PA_RAMP signal provided from EGOLD+
switched with the signals TXONPCN and TXONGSM (V509) to the control ports of
the PA.
The required voltage
BATT+
The required voltage
VCC2.8SW
4522
4521
V1.0
A35-A36-A40
(Baseband H2)
is provided by the battery.
is provided by transistor V435 by using TXON1
from the EGOLD+
(TDMA-Timer H14)
4523
4524
Page 16 of 38
Company Confidential
PA_Comp
is required for
. The resulting voltage is
and V100.
Notes
ICM MP CC ST
09/01

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A36A40

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