Circuits, methods, and apparatus that reduce the peak or maximum EMI
generated by video signals provided to a CRT or digital display monitor.
One exemplary embodiment provides for spreading the spectrum of the video
signal in order to spread or diffuse its peak spectral component. This
may be done by spreading the spectrum of a pixel clock that is used to
clock or time pixel information provided to the monitor. One embodiment
spreads the spectrum of the pixel clock by varying the frequency of its
operation. The pixel clock is generated by a phase-locked loop having a
number of dividers. These dividers divide the frequency of one or more of
the signals around the phase-locked loop. The divide ratio is varied as a
function of time, resulting in a variation of an output signal frequency
as a function of time.