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3. TECHNICAL BRIEF
The 26 MHz clock (X401) consists of a XO (Crystal Oscillator) which oscillates at a frequency of 26 MHz. The
AD6548 requires only an external low cost crystal as the frequency reference. The circuitry to oscillate the
crystal and tune its frequency is fully integrated. The Oscillator is a balanced implementation requiring the
crystal to be connected across 2 pins. There is a programmable capacitor array included for coarse tuning of
fixed offsets (e.g. crystal manufacturing tolerance), and an integrated varactor for dynamic control. The
oscillator is designed for use with a 26MHz crystal. Dedicated control software ensures excellent frequency
stability under all circumstances.
Figure 3.4 CRYSTAL CIRCUIT DIAGRAM
3.3 26 MHz Clock (Crystal, X500)
4
DSX321G-26M
X500
26MHz
1
2
3
