> -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Nick Foster > Sent: Tuesday, February 09, 2010 3:41 PM > To: [email protected] > Subject: [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.
But you don't need to move very much.. A VCTCXO or VCXO might be the ticket for you. A lot of TCXOs have a "trim" input that might be usable. Check the Mouser or DigiKey catalogs. How good does the performance need to be (outside the loop... I assume inside the loop it's disciplined by your 10 MHz reference) A FOX924E has a voltage input and is available as a 16MHz unit (which could be x4 to your 64) Have you considered a straight multiply/add type scheme? Multiply 10 to 60, divide 10 to 1, quadruple to 4, mix 4 with the 60 to get 64. (or some other combination of convenient frequencies..) 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.
