The M906-02 is a Phase-Locked Loop (PLL) based clock generator that uses an internal Voltage Controlled SAW Oscillator (VCSO) to produce a very low jitter output clock. From the M906-02-155.5200, an output clock frequency of 155.52 or 77.76MHz is provided from six LVPECL clock output pairs. (Other frequencies are available; consult the factory.) The accuracy of the output frequency is assured by the internal PLL that phase-locks the internal VCSO to the reference input frequency (19.44MHz for the M906-02-155.5200). The input reference can either be an external crystal, utilizing the internal crystal oscillator, or a stable external clock source such as a packaged crystal oscillator.