xe1205 Semtech Corporation, xe1205 Datasheet - Page 46

• Manufacturer Part Number: xe1205
• Description: Low-power, High Link Budget Integrated Uhf Transceiver
• Manufacturer: Semtech Corporation

For narrow band applications, where users select the lowest frequency deviation and the narrowest baseband filter, the
crystal for reference oscillator of the frequency synthesizer should have the following typical characteristics:
The electrical specifications given in section 4.2.2 are valid for a crystal having the specifications given in Table 34. For
wide band applications requiring less frequency stability, the values for Dfs(0), Dfs(DT), and/or Dfs(Dt) can be relaxed. In
this case foffset + BWssb should be lower than BWfilter, where foffset is the offset (error) on the carrier frequency (the
sum of Dfs(0), Dfs(DT), and/or Dfs(Dt)), BWssb is the single side-band bandwidth of the signal, and BWfilter is the single
side-band bandwidth of the base-band filter.
The overtone crystal usage can result in higher oscillator start-up time than fundamental mode. The overtone crystal
should be designed for Cload = 8 to 10 pF and has parameters of Rm < 60W, C0 < 7 pF.
© Semtech 2007
8.5
Name
Fs
CL
Rm
Cm
C0
Dfs(0)
Dfs(DT)
Dfs(Dt)
REFERENCE CRYSTAL FOR THE FREQUENCY SYNTHESIZER
Description
Nominal frequency
Load capacitance for fs (on-chip)
Motional resistance
Motional capacitance
Shunt capacitance
Calibration tolerance at 25 °C
Stability over temperature range
(-40 °C to 85 °C)
Aging tolerance in first 5 years
Table 34: Crystal characteristics
46
Min. value
-
-
-
-
-
-
-
-
(fundamental)
39.0 MHz
Typ. value
8 pF
-
-
-
-
-
-
XE1205
Max. value
10 ppm
10 ppm
5 ppm
30 fF
7 pF
www.semtech.com
40W
-
-