I haven't exhaustively tested the ADF4107 but I have played with the ADF4002 recently. I haven't been able to come within several dBc/Hz of its rated noise level. In one test, at 100 Hz from an 80 MHz carrier, I've seen about -118 dBc/Hz from the ADF4002 when fed by 10 MHz with -145 dBc/Hz at 100 Hz (which would become about -127 dBc/Hz in an ideal 80 MHz multiplier.) The figure-of-merit equation suggests that -222 + 20*log(8) + 10*log(10 MHz) = -134 dBc/Hz would be achievable, well below the -127 dBc/Hz limit imposed by the reference.
ADISimPLL thinks the figure of merit for the ADF4002 is -216 dBc/Hz rather than -222, so its predicted inband noise of about -122 dBc/Hz is quite a bit closer to my observation. The remaining ~4 dB could be partially bridged by careful tweaking of the drive waveform and input levels to the chip, but the 9 dB needed to get to -127 would be a much bigger leap. Both the old and newer-style Thunderbolts have been tested at around -145 dBc/Hz at 100 Hz, so I think Bob's right in that you can't take full advantage of it with an ADF-series chip. Both the 4002 and 4107 are among the best-rated parts in the lineup. -- john, KE5FX > -----Original Message----- > From: [email protected] [mailto:[email protected]]on > Behalf Of Bob Camp > Sent: Tuesday, March 09, 2010 9:44 AM > To: 'Discussion of precise time and frequency measurement' > Subject: Re: [time-nuts] Realistic Tbolt phase noise > > > Hi > > I think you will find that the noise floor of the ADF4107 (dividers and > phase detector) is a bit higher than -150 at 100 Hz offset at 10 MHz. It > should get you past the -120 level though. That's still much > better than you > are seeing. > > Indeed -120 is not what figure 15 on page 8 of the specification would > imply. I'm sure that the figure is technically correct. It's just not > showing the complete picture. > > Bob > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Christophe Huygens > Sent: Tuesday, March 09, 2010 12:28 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Realistic Tbolt phase noise > > Hi, > > I am using an ADF4107 and a Crystek resonator, with a LBW of > a few 100 Hz. It behaves perfect outside the loop, but inside the > loop it is too noisy (not too important for my application, but > just curious). > > I ll try to measure the Thunderbolt directly at 10Mhz, but the > my HP 11729C needs some mods for this. > > Christophe > > > On 09/03/10 18:21, Bob Camp wrote: > > Hi > > > > How are you multiplying it to 1 GHz and checking it? > > > > I've seen multipliers that have issues beyond about -130 at 100 Hz. It's > not > > common, but it can happen. > > > > ------------------ > > > > The supply provided by TAPR is a pretty basic unit. It would > not surprise > me > > if some were better than others. They also may work better on US mains > > voltage than they do on international voltages. I would rig up another > > supply and see what happens. That would at least rule out the > supply as an > > issue. > > > > In a previous post the idea of putting a 7805 and 7812 regulator on the > > TBolt came up. If you have +14 available that seems like the > best thing to > > try. > > > > Bob > > > > -----Original Message----- > > From: [email protected] [mailto:[email protected]] On > > Behalf Of Christophe Huygens > > Sent: Tuesday, March 09, 2010 7:50 AM > > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] Realistic Tbolt phase noise > > > > This is with the power supply as provided by TAPR so should be ok. > > > > Xtof. > > > > > > On 09/03/10 13:44, Bob Camp wrote: > > > >> Hi > >> > >> Power supply noise would be the first thought. > >> > >> Next up would be grounding inside the Thunderbolt (card to case, > >> > > connectors to case). > > > >> Bob > >> > >> > >> On Mar 9, 2010, at 7:32 AM, Christophe Huygens wrote: > >> > >> > >> > >>> Hi, > >>> > >>> I noticed several vendors on Ebay have the t-bolt on sale. > >>> > >>> However, the once showing their own PN plots seem to get only > >>> -115, -120 dBc/Hz at 100Hz. Yet, > >>> http://www.leapsecond.com/pages/tbolt/noise.htm seems > >>> to have mucht better results: up to -150 depending on > >>> power supply. > >>> > >>> By multiplying to 1GHz I also seem to be getting something > >>> like -75 or - 80 rather than -110. > >>> > >>> Any thoughts? > >>> > >>> Christophe > >>> on4iy > >>> > >>> > >>> > >>> _______________________________________________ > >>> 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. > > > > > _______________________________________________ > 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.
