Sinusoidal Waveform as Reference Clock Signal





Question: Can sinusoidal waveform be used as reference clock signal for Clock Buffer or Clock Synthesizer?

Response: Any shape of Waveform can trigger clock device if signal value goes below VILmax and above VIHmin values. Sinusoidal waveform is a good clocking source without high frequency harmonics.

Following points need to consider while using sinusoidal signal as reference clock:
1.Input sinusoidal signal should have offset voltage equal to peak voltage of sinusoidal signal; this will result in pk-pk waveform on dc ground of clock chip and so no negative input voltage.  

2. Peak to Peak voltage of sinusoidal signal should be equal to recommended input voltage of reference signal as per datasheet.

2. There is a possible difference in propagation delay (Tpd) from what specified in data sheet because sinusoidal waveform is slow in transition from one state to another. As input voltage rises or falls, the input current increases or decreases respectively.

3. A clean sinusoidal waveform is a good clock source with low jitter. Crystal generates sinusoidal waveforms.