Undersampling and Clock Source Sensitivity: How Input Frequency Affects SNR Degradation

Undersampling increases the requirement for the clock source, and the sensitivity to clock jitter or phase noise becomes more significant as the input frequency increases. For instance, if a clock source reduces the signal-to-noise ratio (SNR) of a full-scale signal by 1dB at 70MHz, it will reduce SNR by 3dB at 140MHz and 4.5dB at 190MHz.