V1.0 Page 16 of 38 ICM MP CC ST
A35-A36-A40 Company Confidential 09/01
4.5.2 Transmitter : Power Amplifer Amplifier and Antenna Switch
Splited by a discrete circuit into EGSM900 and GSM1800, the TXVCO output signal Notes
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 PA_Comp is required for
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+(Baseband H2). The resulting voltage is
switched with the signals TXONPCN and TXONGSM (V509) to the control ports of
the PA.
The required voltage BATT+ is provided by the battery.
The required voltage VCC2.8SW is provided by transistor V435 by using TXON1
from the EGOLD+(TDMA-Timer H14) and V100.
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