RH-13
Troubleshooting
CCS Technical Documentation
Page 66
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Nokia Corporation
Issue 1 11/02
BB PLL
The BB PLL generates RF clock to base band. It has two fixed frequencies 77.76 MHz in
TDMA mode and 78 MHz in GSM mode. Next picture shows BB PLL working.
Figure 46: BB PLL.
Freq/Phase
comparator
Charge Pump
Divider
324 or 325
Divider 4 or 6
Loop Filter
Varactor
Resonator
Active
part
BB VCO
Divider
65 or 80
VCTCXO
19.2 MHz
RF-IC
RFCLK to BB
GSM 13 MHz
TDMA 19.44 MHz
* Data
*Data are related to vctcxo frequency and mode selections.