IMHO it'd be best not to roll your own crystal oscillator unless you have the equipment to measure its noise and other performance parameters, and the time/skills/interest to optimize it. That's a tunnel in the rabbit hole that will just take you away from the one you're headed down now. For a one-off project you can often find good parts on eBay just by searching on "mhz oscillator" (without the quotes). Remember that you have the luxury of not being married to a particular frequency, in an SDR application.
For new parts, Crystek makes some good VCXO parts that are easy to get from DigiKey, and you could also look at Valpey-Fisher's ovenized VFOV110 line for better performance. Watch the residual noise specs of the ADCs and DDSes to make sure you're not paying for a low noise floor that you can't take advantage of. -- john, KE5FX > -----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. 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.
