Transmitter (Tx) - Nokia 301 Service Manual

RM-839; RM-840; RM-841
System Module
Figure 66 The functional block diagram of reference clock
Supply for External VCTCXO Module
The power supply for the external TCVCXO module is routed through the PMB 5707 chip since the module is
switched on and off via its power supply instead of an additional dedicated control line. The supply voltage
XO_SUP for the TCVCXO module is activated by pulling one of the external control lines REF_CLK_EN, SYS_CLK_EN,
FSYS2_EN or FSYS3_EN to high or by activating at least one of the three FSYS clock output buffers by
programming.
AFC_DAC (Automated Frequency Control)
For the adjustment of the reference frequency to the correct value imposed by a cellular network, the external
TCVCXO module is tuned. This is done by means of an analog control voltage that is part of an AFC loop
controlled by the baseband. The control voltage is generated by an integrated 12 Bit D/A-Converter.

Transmitter (TX)

The transmitter chain consists of the following blocks:
• SMARTi UEmicro transmitter part
• PA
• FEM
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