Nokia c2-00 Service Manual page 161

RM-704
System Module
X-TAL/DCXO
The X-Tal and DCXO is the 26MHz Reference Clock used by the entire platform as an accurate clock. The clock
frequency can be controlled and adjusted by the embedded capacitor bank of the DCXO (Integrated in the X-
GOLD213). During synchronization to base-station or base-station emulator (Normal mode/signalling mode)
the accuracy of the clock should be max 0.1ppm, however in normal mode the accuracy can be ±60ppm
depending on the setting of the AFC DAC value.
Antenna detection
The antenna detection circuit is applied to determine if the antenna is mechanically mounted or not. The
antenna circuitry consist by a current sourced ADC from the X-Gold, that's are sourcing the resistors R7454
and R7460 to the antenna pad E7454. The antenna has an 0 impedance @ DC to GND if mounted correctly.
The ADC (embedded in the X-GOLD213) measured the voltage and use this to evaluate if the antenna is
mounted or not, and if the antenna connection to the pad E7454/E7453 is okay or not. The detailed circuit
is shown in the figure below.
Figure 74 Antenna detection circuit
FEM ID/PA ID
The FEM ID (PA ID) is used for FEM identification depending on the different release, see Table 2 . For more
info regarding the FEM ID see Appendix E.
Issue 1 COMPANY CONFIDENTIAL Page 5 – 27
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