Timing jitter in digital filtering of analog signals

Abstract

Effects of timing jitter in digital filtering of analog signals are analyzed. Jitter may be introduced into the system when the incoming analog signal is being sampled and when the samples of the output of the digital filter are being read out for reconstruction back into an analog signal. These two jitters are called readin and readout jitters, respectively. General expressions are derived for the spectrum of the analog output in the presence of jitter and for the mean-square error introduced by the jitter. Four specific cases are then considered. They are readin jitter only, readout jitter only, independent jitter, and locked jitter. In each case, the general expression for the spectrum of the analog output is reduced to a more explicit form, and a simple upper bound on the mean-square error is derived. An example is included to illustrate the effect of high-frequency jitter and the effect of jitter due to 60-cycle pickup.