[time-nuts] Distribution amplifier phase noise
Gentlemen, although it has been discussed here by Bruce et al how the noise floor of integrated distribution amplifiers designs may compare to discrete designs I have never seen a *real* phase noise measurement of a *real* amplifier here. My own measurements on a DIY AD8007 based distribution amplifier indicate a noise floor of abt. -160 dBc @ 100 kHz which may not meet the specs of the absolutely top line of oscillators by some 15 dB but is well in reach of Bruce's predictions for integrated designs. Did any of you Timepod owners make measurements of your own on amplifier noise? Please note that I am not only out for the noise floor specs. Instead I am specially interested in specs for power supply induced spurs. I just received an article covering ultra low noise oscillators to be found here: http://www.crystek.com/documents/appnotes/ImpactUltralow.pdf Clearly the phase noise diagram shows a power induced spur @ -100 dBc. Is this the measure for the amplifier to take care for? I.e. if the amplifiers has spurs down -120 dBc, is that good enough? Or to put it another way: What is the best phase noise that we can expect from an amplifier concerned power supply induced spurs? Can it be that the spurs to be seen are not a problem of the amplifier itself but are inherent to the measurement setup? If so, is there a recommended setup to minimize such problems? Thanks in advance for your suggestions. I appreciate the expertise in this group a lot! Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amplifier phase noise
Ulrich, I'm on the run right now, but I've done measurements of the HP 5087, TADD-1, Spectracom 8140-series line amp, and a new protoype ULN buffer amp. I'll post the links later today. John On Mar 14, 2013, at 6:59 AM, Ulrich Bangert df...@ulrich-bangert.de wrote: Gentlemen, although it has been discussed here by Bruce et al how the noise floor of integrated distribution amplifiers designs may compare to discrete designs I have never seen a *real* phase noise measurement of a *real* amplifier here. My own measurements on a DIY AD8007 based distribution amplifier indicate a noise floor of abt. -160 dBc @ 100 kHz which may not meet the specs of the absolutely top line of oscillators by some 15 dB but is well in reach of Bruce's predictions for integrated designs. Did any of you Timepod owners make measurements of your own on amplifier noise? Please note that I am not only out for the noise floor specs. Instead I am specially interested in specs for power supply induced spurs. I just received an article covering ultra low noise oscillators to be found here: http://www.crystek.com/documents/appnotes/ImpactUltralow.pdf Clearly the phase noise diagram shows a power induced spur @ -100 dBc. Is this the measure for the amplifier to take care for? I.e. if the amplifiers has spurs down -120 dBc, is that good enough? Or to put it another way: What is the best phase noise that we can expect from an amplifier concerned power supply induced spurs? Can it be that the spurs to be seen are not a problem of the amplifier itself but are inherent to the measurement setup? If so, is there a recommended setup to minimize such problems? Thanks in advance for your suggestions. I appreciate the expertise in this group a lot! Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Distribution Amplifier Phase Noise
Hello, Here's a timepod plot of my own amplifier that my company sells www.ptsyst.com/phasenoise.pdf Note this is a distribution amplifier with about 7 dB of gain. We can get the floor to about -174 dBc if we reduce the gain to unity. Best Regards Martyn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amplifier phase noise
Ulrich Bangert wrote: Gentlemen, although it has been discussed here by Bruce et al how the noise floor of integrated distribution amplifiers designs may compare to discrete designs I have never seen a *real* phase noise measurement of a *real* amplifier here. My own measurements on a DIY AD8007 based distribution amplifier indicate a noise floor of abt. -160 dBc @ 100 kHz which may not meet the specs of the absolutely top line of oscillators by some 15 dB but is well in reach of Bruce's predictions for integrated designs. Did any of you Timepod owners make measurements of your own on amplifier noise? Please note that I am not only out for the noise floor specs. Instead I am specially interested in specs for power supply induced spurs. I just received an article covering ultra low noise oscillators to be found here: http://www.crystek.com/documents/appnotes/ImpactUltralow.pdf This paper is very sloppily written. e.g.: -174dBm/Hz is the available thermal noise power of any resistor at 290K not just 1 ohm. There is no explicit consideration of the contribution of thermal noise power to phase noise. Clearly the phase noise diagram shows a power induced spur @ -100 dBc. Is this the measure for the amplifier to take care for? I.e. if the amplifiers has spurs down -120 dBc, is that good enough? Or to put it another way: What is the best phase noise that we can expect from an amplifier concerned power supply induced spurs? Can it be that the spurs to be seen are not a problem of the amplifier itself but are inherent to the measurement setup? If so, is there a recommended setup to minimize such problems? I routinely achieve mains related PN spurs below -150dBc and often below -170dBc. Such spurs can be enhanced by low frequency ground loops and magnetic fields. Using RF isolation transformers with capacitive grounding of the isolated winding helps considerably in suppressing mains related ground currents. Thanks in advance for your suggestions. I appreciate the expertise in this group a lot! Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amplifier phase noise
Am 14.03.2013 19:02, schrieb Bruce Griffiths: This paper is very sloppily written. e.g.: Yes, actually. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amplifier phase noise
I think designing a good distribution amp is much more difficult then it would seem at first glance. But placing it in a system is the real challenge. If you have a ULN 5MHz oscillator that has phase noise of -125dB @ 1Hz and a noise floor of 167dB @10KHz it will take some real attention to detail from cable to amp design to get that signal to it's destination. I have done some past measurements and for BVA's and top of the line Wenzels, few distribution amps are up to the task. Symmetricom has data sheets on their amps and they vary widely close in. the 4036B seems like the was to go from them. The PTS amp also looks exceptional. I think Quartzlock also makes a great dist amp. I am sure there are others. I am currently setting up a new multiple reference system and seeing all kinds of artifacts. Channel isolation and cable interaction can really affect signal quality even higher end Pomona act like soaker cables. I think it is as much art as science where things like equipment gr ounding and isolated or unisolated patch panels can reduce or contribute to noise depending on very minor variables. And what effect does having the equipment net worked have? Are there any basic rules of thumb as far as dist amp set-up? Thomas Knox Date: Fri, 15 Mar 2013 07:02:44 +1300 From: bruce.griffi...@xtra.co.nz To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amplifier phase noise Ulrich Bangert wrote: Gentlemen, although it has been discussed here by Bruce et al how the noise floor of integrated distribution amplifiers designs may compare to discrete designs I have never seen a *real* phase noise measurement of a *real* amplifier here. My own measurements on a DIY AD8007 based distribution amplifier indicate a noise floor of abt. -160 dBc @ 100 kHz which may not meet the specs of the absolutely top line of oscillators by some 15 dB but is well in reach of Bruce's predictions for integrated designs. Did any of you Timepod owners make measurements of your own on amplifier noise? Please note that I am not only out for the noise floor specs. Instead I am specially interested in specs for power supply induced spurs. I just received an article covering ultra low noise oscillators to be found here: http://www.crystek.com/documents/appnotes/ImpactUltralow.pdf This paper is very sloppily written. e.g.: -174dBm/Hz is the available thermal noise power of any resistor at 290K not just 1 ohm. There is no explicit consideration of the contribution of thermal noise power to phase noise. Clearly the phase noise diagram shows a power induced spur @ -100 dBc. Is this the measure for the amplifier to take care for? I.e. if the amplifiers has spurs down -120 dBc, is that good enough? Or to put it another way: What is the best phase noise that we can expect from an amplifier concerned power supply induced spurs? Can it be that the spurs to be seen are not a problem of the amplifier itself but are inherent to the measurement setup? If so, is there a recommended setup to minimize such problems? I routinely achieve mains related PN spurs below -150dBc and often below -170dBc. Such spurs can be enhanced by low frequency ground loops and magnetic fields. Using RF isolation transformers with capacitive grounding of the isolated winding helps considerably in suppressing mains related ground currents. Thanks in advance for your suggestions. I appreciate the expertise in this group a lot! Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amplifier phase noise
Hi There are some good old NIST papers on distribution amps using 2N3904 / 2N3906's. There are also some newer enhanced versions that improve things a bit. They are quite capable of handling a modern ULN OCXO. There are also other approaches using completely different discrete devices. The real question is - what are you trying to do? / What environment are you operating in? Having 64 outputs with 180 db isolation, and better than -160 dbc / Hz at 1 Hz sounds cool, but is that what you need? It's certainly not needed for driving any equipment I'm aware of. About the only application would be running 64 phase noise test sets all at one time. Something costing 1/100th as much might be good enough…. Most commercial distribution setups are aimed at driving gear like counters. Any thing past a hundred hertz is rejected by the reference circuit in the gear. On a good counter the roll off might start a lot lower than that. Low broadband noise isn't of any use. The same loop bandwidth / loop gain / local reference noise combination also impacts the usefulness of an uber good 1 second ADEV floor. 74AC04 inverters (or similar parts) are quite adequate for buffering the reference into 99% of the gear out there. Something less than $1 an output for everything including the pert board. Bob On Mar 14, 2013, at 4:00 PM, Tom Knox act...@hotmail.com wrote: I think designing a good distribution amp is much more difficult then it would seem at first glance. But placing it in a system is the real challenge. If you have a ULN 5MHz oscillator that has phase noise of -125dB @ 1Hz and a noise floor of 167dB @10KHz it will take some real attention to detail from cable to amp design to get that signal to it's destination. I have done some past measurements and for BVA's and top of the line Wenzels, few distribution amps are up to the task. Symmetricom has data sheets on their amps and they vary widely close in. the 4036B seems like the was to go from them. The PTS amp also looks exceptional. I think Quartzlock also makes a great dist amp. I am sure there are others. I am currently setting up a new multiple reference system and seeing all kinds of artifacts. Channel isolation and cable interaction can really affect signal quality even higher end Pomona act like soaker cables. I think it is as much art as science where things like equi pment gr ounding and isolated or unisolated patch panels can reduce or contribute to noise depending on very minor variables. And what effect does having the equipment net worked have? Are there any basic rules of thumb as far as dist amp set-up? Thomas Knox Date: Fri, 15 Mar 2013 07:02:44 +1300 From: bruce.griffi...@xtra.co.nz To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amplifier phase noise Ulrich Bangert wrote: Gentlemen, although it has been discussed here by Bruce et al how the noise floor of integrated distribution amplifiers designs may compare to discrete designs I have never seen a *real* phase noise measurement of a *real* amplifier here. My own measurements on a DIY AD8007 based distribution amplifier indicate a noise floor of abt. -160 dBc @ 100 kHz which may not meet the specs of the absolutely top line of oscillators by some 15 dB but is well in reach of Bruce's predictions for integrated designs. Did any of you Timepod owners make measurements of your own on amplifier noise? Please note that I am not only out for the noise floor specs. Instead I am specially interested in specs for power supply induced spurs. I just received an article covering ultra low noise oscillators to be found here: http://www.crystek.com/documents/appnotes/ImpactUltralow.pdf This paper is very sloppily written. e.g.: -174dBm/Hz is the available thermal noise power of any resistor at 290K not just 1 ohm. There is no explicit consideration of the contribution of thermal noise power to phase noise. Clearly the phase noise diagram shows a power induced spur @ -100 dBc. Is this the measure for the amplifier to take care for? I.e. if the amplifiers has spurs down -120 dBc, is that good enough? Or to put it another way: What is the best phase noise that we can expect from an amplifier concerned power supply induced spurs? Can it be that the spurs to be seen are not a problem of the amplifier itself but are inherent to the measurement setup? If so, is there a recommended setup to minimize such problems? I routinely achieve mains related PN spurs below -150dBc and often below -170dBc. Such spurs can be enhanced by low frequency ground loops and magnetic fields. Using RF isolation transformers with capacitive grounding of the isolated winding helps considerably in suppressing mains related ground currents. Thanks in advance for your suggestions. I appreciate the expertise in this group a lot! Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243
