Design of Down Scalers in Mixed-Signal GHz Frequency Synthesizer

An optimized method is presented to design the down scalers in a GHz frequency synthesizer.The down scalers are comprised of dual modulus prescaler (DMP) and programmable & pulse swallow divider,different methods of high frequency analog circuit and digital logical synthesis are adopted respectively.Using a DMP high speed,lower jitter and lower power dissipation are obtained,and output frequency of 133.0MHz of the DMP working at divide-by-8 shows an RMS jitter less than 2ps.The flexibility and reusability of the programmable divider is high;its use could be extended to many complicated frequency synthesizers.By comparison,it is a better design on performance of high-frequency circuit and good design flexibility.