cool. I found Xilinx CPLD's mounted up on through-hole boards for $18.00 at Digilent. I have other Digilent products and they're good... Don
Nick Foster > > That's a great suggestion, Ulrich. Thanks. It took all of five minutes to > implement in VHDL, and looks great. > > I also found Fox's "Xpresso" line of miniature synthesized VCXOs, and the > numbers look pretty compelling. CMOS output, too. And, the best part, > they're available off-the-shelf. Does anyone have experience with these in > low-noise applications? They're ludicrously expensive (Digikey lists them > for $47/ea in short qty), but if I can get some samples from Fox, it'll > save me a lot of grief. > > I'll let you all know how it works out, and Don, if I get samples and they > work OK I'll mail you some. > > Nick > >> From: [email protected] >> To: [email protected] >> Date: Wed, 10 Feb 2010 09:02:30 +0100 >> Subject: Re: [time-nuts] Low phase noise VCO >> >> Nick, >> >> altough you have been asking for advice for the VCO I would like to draw >> your attention on how you can improve your phase detector. >> Edge-triggered >> phase detectors are not bad, the even can work as frequency detectors if >> you >> are far from lock and help you to gain lock where a XOR would not. >> However, >> once you are CLOSE to a phase lock, a simple XOR makes the better phase >> detector with less phase noise. There is a VERY easy circuit that >> marriages >> the best of both worlds. Google for the AD9901 frequence/phase detector >> and >> mimic their schematic of the first page into your CPLD. Have done this >> with >> different CPLDS from XILINX and ALTERA and has always worked very well >> for >> me in terms of frequency locking range and low phase noise. >> >> Best regards >> Ulrich Bangert >> >> > -----Ursprungliche Nachricht----- >> > Von: [email protected] >> > [mailto:[email protected]] Im Auftrag von Nick Foster >> > Gesendet: Mittwoch, 10. Februar 2010 00:41 >> > An: [email protected] >> > Betreff: [time-nuts] Low phase noise VCO >> > >> > >> > >> > Gentlemen, >> > >> > Not being an oscillator guru, I thought I'd ask here. I'm >> > building up a fixed-frequency 64MHz PLL oscillator which uses >> > a 10MHz reference. The reference is a homebrew HP >> > 10544A-based GPSDO which seems to work OK. I've built a phase >> > comparator based on a CoolRunner-II CPLD which implements a >> > flip-flop phase-frequency comparator just like the CMOS 4046. >> > Seems to work great, although I haven't put it to the test >> > yet with respect to phase noise. So all I need now is the VCO. >> > >> > Right now, all I need is 64MHz to clock a software-defined >> > radio, so I was thinking about using a VCXO. I see lots of >> > solutions using LC oscillators, but very few using crystals >> > because overtone crystals can't be pulled very far at all. So >> > my question is, what type of oscillator would you recommend >> > for this project, an overtone crystal oscillator like a >> > Butler, or an LC oscillator? Is there a particular oscillator >> > topology you favor, or (better yet) a schematic of one you like? >> > >> > Thanks, >> > Nick >> > >> > _________________________________________________________________ >> > Hotmail: Powerful Free email with security by Microsoft. >> > http://clk.atdmt.com/GBL/go/201469230/direct/01/ >> > _______________________________________________ >> > time-nuts mailing list -- [email protected] >> > To unsubscribe, go to >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _________________________________________________________________ > Hotmail: Free, trusted and rich email service. > http://clk.atdmt.com/GBL/go/201469228/direct/01/ > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
