Use an sampling phase detector ... a pair of fast diodes gated on with a short pulse ( say 100 ps) will work into the multipal GHz range ... sample at the reference rate (can be in the KHz to hundreds or thousands of MHz with some step recovery diodes) when phase locked, the sampler output will be a DC voltage to control the VCO or VCXO ... Jim KI6MZ
--- In [email protected], "jr_dakota" <[EMAIL PROTECTED]> wrote: > > That's the max frequency of the divider circuits, the phase comparator > works at a much much lower frequency after division of both the > reference and the VCO ... > > What we are looking at is a 1 to 1 phase comparison (no divders) up to > 50-60Mhz ... for example set the DDS at 30 mhz and the VCO tracks at > 30Mhz so the phase comparator works for both signals at 30 Mhz > > JR > > --- In [email protected], F6EHJ <[EMAIL PROTECTED]> wrote: > > > > Hi JR, > > > > Look at the MC145170, 185 MHz is the upper limit with 500mV at its > input. > > Not too much easy to speak with it... > > > > Best regards, > > > > Gérard/F6EHJ > > > > jr_dakota a écrit : > > > > >Given the State of the Art, 50Mhz phase detectors are probably > > >possible fairly easily.... > > > > > >Problem is everything commercial is geared for 900Mhz cellphones, > > >gigahertz broadband wireless, etc and it's not possible at those > > >frequencies (yet) for 1 on 1 phase comparison. The 50Mhz and under > > >market is way too small to make anyone want to develop such an IC ... > > > > > >JR > > > > > >--- In [email protected], "sis108" <[EMAIL PROTECTED]> wrote: > > > > > > > > >>I often wondered why you couldn't use a 1x VCO and phase detctor. > > >> > > >>IE DDS 50-60Mhz out VCO 50-60MHZ both phase detectors 50-60mhz in. > > >>Hopefully the loop filter would kill the spurs. > > >> > > >>I have not found high speed phase/freq detectors however. > > >> > > >>Anyone have an opinion on how well this might work to kill the spurs? > > >> > > >> > > >>--- In [email protected], KY1K <[EMAIL PROTECTED]> wrote: > > >> > > >> > > >>>Has any amateur ever done a DDS in conjunction with a PLL to > clean up > > >>>spurs? I hear chatter about it working well if the PLL is designed > > >>>properly, but have never run across any real life examples of the 2 > > >>>technologies rolled into one. > > >>> > > >>>I understand the DDS has advantages, especially in it's ability to > > >>>change frequency quickly. But, if rapid qsy's are not needed, I > would > > >>>think a PLL with a slow response time in the filter would be as good > > >>>or better with respect to spectral purity than any DDS available > > >>> > > >>> > > >today. > > > > > > > > >>>Appreciate any pointers to web resources discussing this topic. > > >>> > > >>>Thanks, > > >>> > > >>> > > >>>Art > > >>> > > >>> > > >>> > > > > > > > > > > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > >--------------------------------------------------------------------------------------- > > >Wanadoo vous informe que cet e-mail a ete controle par > l'anti-virus mail. > > >Aucun virus connu a ce jour par nos services n'a ete detecte. > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
