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4-3 Transmitter Section
POWER AMP MMIC
Power Amp MMIC (U407) amplifies signal to be
sent out to the base station through the antenna.
DRIVER AMP
The driver amp (Q413) allows the input signal to
the power amp MMIC(U407) to be within a
specified level.
UP CONVERTER (MIXER)
The up-converter (U405) receives the first local
signal to generate 1880°æ30MHz from the signal
controlled by TX AGC amp (U404). 1880°æ30MHz
signal comes out of the mixer output by adding
130.38MHz IF signal to 1749.62°æ30MHz first local
signal. The driver amp's reference number is Q413
and up converter's reference number is U405.
IF AUTOMATIC GAIN CONTROLLER AMP
The signal output from BBA (Base Band ASIC)
should be a constant level. The TX IF AGC amp
(U404) controls power to keep the signal at a
desired level. Dynamic range is 85 dB, up gain
+40dB, and down gain -45dB.
POWER SUPPLY REGULATOR
The power supply regulator (U414) generates the
regulated power.
Samsung Electronics
ANTENNA
ANT1 allows signals to send and to receive to
from the base station.
RF BAND PASS FILTER (BPF)
The RF BPFS (F402, F403) accept only a specific
frequency (1880°æ30MHz) to send it out to power
amp MMIC. The bandwidth is 60MHz.
POWER SUPPLY SWITCHING
Power supply switching (Q412) turns on TX
POWER when the phone is in traffic mode and
supplies power to the circuits.
ISOLATOR
Isolator (I401) is used to reduce a reflected signal
to protect the power amp MMIC from being
damaged.
POWER SUPPLY REGULATOR
The power supply regulator (U413,U414) supplies
a regulated power to each part of transmitter.
U413 supplies 4.8V to Tx driver (Q413) and Power
Amp MMIC (U407). U414 supplies 4.2V to the
others.
Circuit Description
4-5
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