I use AD6645 evaluation board which has 105 MHz cyrstal to sample analog signal. I send sampled signal to a computer and plot that. The signal below which is at 200 KHz is sampled by AD6645 . The sine wave is generated by Agilent waveform generator. As you see on the plot, I sometimes get spike on the signal. I use rising edge of DRY pin to receive 14 bits data. What could be the reason for this spikes?