THis is exactly what they are talking about the 74HC390 can do over 50MHz and costs abut 30 cents. You don't need ECL or anything so exotic the 30 cent part will work. Set it for divide by 5. I guess this is imperfect enough that there is some fourth harmonic content in the 2MHz square wave, then you select that with a narrow band filter and amplify it to whatever you need. A smart design might try and add fourth harmonics be using a slightly not-symetric 2MHz square wave
My question is about the phase noise of the final 16MHz signal. Do crystal filters "clean up" the signal. It seems that after several 16MHz crystals in series the output should look a lot like an XO. On Thu, Jan 3, 2013 at 6:02 PM, Tom Miller <[email protected]> wrote: > Isn't there a fast divide by N counter that you could set to 10? Maybe even > in ECL? > > > ----- Original Message ----- From: "David" <[email protected]> > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Sent: Thursday, January 03, 2013 8:49 PM > Subject: Re: [time-nuts] 10 MHz -> 16 MHz clock multiplier > > > > They do not exist as I found out (again) not long ago. The last 7490 > made was LS (low power schottky) and I use quite a few of them. > Actually, I have seen a datasheet for a 74HC90 and 74HCT90 but they > apparently either never went into production or very few were > produced. > > The closest non-TTL alternative that I found was the 74HC390 or > 74HCT390 which is basically two 7490 counters in one package. > > On Fri, 04 Jan 2013 11:59:01 +1100, Max <[email protected]> wrote: > >> Where can one get some of these mythical 74HC90 's and 74AC90 's that >> have been mentioned. >> None of the usual places have them, ie ebay, digi-key, farnell, or >> even the Chinese. >> Also data-sheets are not to be found. >> Thanks >> >> >> >> On 4/01/2013 5:13 AM, Bill Fuqua wrote: >>> >>> One way is to divide by 10 and then multiply by 16. >>> Divide by 10 and then follow by 4 tuned frequency doublers. >>> This should introduce little phase noise. >>> Another way to do it is to divide by 10, then pass the output thru a >>> narrow 16 MHz filter and amplify. Sounds difficult but the filter can >>> be one >>> or two 16 MHz crystals followed by a simple amplifier. Look at the >>> reference input circuit for a PTS-160. The output of the divide by 10 >>> needs to >>> be asymmetrical so it produces even harmonics. If you are using a >>> divide divide by 5&2 such as a 74HC90, divide by 2 first then by 5. >>> Ideally the pulse width should be a half period of 16 MHz for the >>> maximum harmonic content at 16 MHz. >>> You can take the output of the frequency divider and send it to a >>> NAND gate. >>> One input of the gate is directly connected and the other is delayed. >>> You can >>> use an RC with a variable capacitor to ground to get it just right. >>> Just adjust the capacitor to get the maximum output from your >>> filter amplifier. >>> 73 >>> Bill wa4lav >>> >>> >>> >>> At 07:41 PM 1/2/2013 +0000, you wrote: >>>> >>>> What's the simplest way to generate 16 MHz from 10 MHz? This will be >>>> for clocking a microcontroller at 16 MHz given 10 MHz (Cs/Rb/GPSDO). >>>> Low price and low parts count is a goal; jitter is not a concern but >>>> absolute long-term phase coherence is a must. >>>> >>>> The ICS525 (as in TAPR Clock-Block) is a good candidate but I was >>>> wondering if there's something cheaper, less functional, and maybe >>>> not SSOP. Any suggestions? >>>> >>>> Thanks, >>>> /tvb >>> >>> >>> >>> _______________________________________________ >>> 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. > > > _______________________________________________ > 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. -- Chris Albertson Redondo Beach, California _______________________________________________ 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.
