A digital circuit generates very precise varying clock frequencies for
applications that can tolerate a small degree of jitter but require exact
longer term frequencies, e.g. a video clock for a laser printer. Some
subpixel jitter is acceptable, but the overall pixel rate remains exact
and consistent. In some applications, the jitter may be desirable to
smear the EMI spectrum. For example, if the high frequency input clock is
modulated, the edges of the video clock will also be modulated yet remain
within the jitter and frequency specification.