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Transmit modes should always use fø = 200kHz. The IF and RF output frequencies are set by
programming the N-Divider registers and also programmed via 3-wire interface with external system
controller.
RF_Lo(Rx)
3.2.5. Transmitter Part
The Transmitter part contains Si4200-BM[U502] active parts, Power Amp Module[U504] and Antenna
switch[FL501].
The transmit section of Si4200-BM [U502] consists of an I/Q baseband upconverter, an offset phase-
locked loop (OPLL) and two 50 ohm output buffers that can drive external power amplifiers.
The RF GMSK outputs from the transmit VCO are fed directly to the RF power amplifiers.
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 Antenna Switch.
Figure 2. Synthesizer Block
U505/Si4133T
RF1
RF2
RF_Lo(Tx)
IF_Lo(Tx)
IF
IF
PLL
PLL
IF
-16-
Baseband
Baseband
U506
VC-TCXO
13MHz
(TI)
(TI)
U102
U102
IOTA
IOTA
+
+
U101
U101
Calypso
Calypso
(CO35)
(CO35)
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