A PLL based Clock Generator with Improved EMC

Periodic signals used in electronic circuits, in particular high frequency clock signals, are a major cause of electromagnetic interference. Since it has been shown that such interferences can be reduced by introducing a suitable modulation, we present the implementation of a PLL-based clock generator with a built-in frequency modulator. The circuit is designed to obtain a fast modulation with a chaotic binary modulating signal, which has been shown to be extremely effective in lowering spectrum peaks.