Transmitter: Power Amplifier - Siemens C45 Repair Documentation

4.5.2 Transmitter: Power Amplifier

The output signal (PCN_PA_IN) from the TX-VCO are led to the power amplifier
(Z900) passing a matching circuit. The PA is a "two in one" PA (GSM part not used)
and, is connected directly to Batt+.
After amplification, a part of the output signal (TX_PCN_OUT) is decoupled via a
directional coupler. The other part runs through the antenna switch (Z880) and the
antenna connector (X870) to the Antenna. The decoupled part is equalised by the
detector diode (V920) and used from the (N920) to get a PA control voltage by
comparing this voltage with the PA_RAMP signal provided from the
EGOLD+ (
GAIM/BASEBAND H2
The (N920) is activated through the signal
The required voltage BATT+
The required voltage VCC2_8
Blockdiagram of LML361 (PA control IC9
Vhome
Vdd
Vf
Vr
Ramp
TC
Gnd
V1.0
C45, M50 AND MT50
).
TXONPA
is provided by the battery.
is provided by N840.
Comp1
Page 21 of 46
Company Confidential © Copyright Siemens AG
and TXON1.
PA_ON
Vdd
Comp 2
BS Vdd Vss
Vdd
Vss
Vdd
Out A
Vss
Vdd
Out B
Vss
ICM MP CCQ ST
05/02