Re: [time-nuts] Advantages of differential oscillator structures?
BTW, the venerable Motorola MC12061 oscillator is a bipolar version of this circuit. It was good for audio clocks in the 12 MHz range, including VCXOs using a series varactor. David On 8/10/13 2:34 PM, Bob Camp wrote: Hi Any bets on weather or not they have actually designed a 12.8 MHz multivibrator that injection locks to the crystal? Pretty hard with discrete parts, but not out of the question with silicon. You'd have to get their spice (or what ever) files to figure it out ... Bob On Aug 10, 2013, at 12:03 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? Cheers, Magnus ___ 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 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] Advantages of differential oscillator structures?
Hi, While reading up on oscillator circuits i stumbled over differential oscillator structures (see [1] for example). But sofar i have been unable to figure out what the exact advantages of a differential oscillator strucutre in general are. Would someone here be so kind and give me some hints where to look? Thanks in advance Attila Kinali [1] A High-Stability, Ultra-Low-Power Differential Oscillator Circuit for Demanding Radio Applications, by David Ruffieux, 2002 http://www.imec.be/esscirc/ESSCIRC2002/PDFs/C02.01.pdf http://www.imec.be/esscirc/ESSCIRC2002/presentations/Slides/C02.01.pdf -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Advantages of differential oscillator structures?
Hi Attila, I gather you did not fully read the paper ? In normal CMOS circuits, the higher the oscillator frequency the higher the amount of current drawn to reach that higher frequency. So, the two oscillator system was used to keep time and wake up the higher frequency oscillator (for example the 12.8 MHz) when the radio was in operation. When not in operation just the lower frequency oscillator (32 KHz) was used to keep time and provide a wake of the microprocessor and the higher frequency oscillator needed for the radio operation. This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. BillWB6BNQ Attila Kinali wrote: Hi, While reading up on oscillator circuits i stumbled over differential oscillator structures (see [1] for example). But sofar i have been unable to figure out what the exact advantages of a differential oscillator strucutre in general are. Would someone here be so kind and give me some hints where to look? Thanks in advance Attila Kinali [1] A High-Stability, Ultra-Low-Power Differential Oscillator Circuit for Demanding Radio Applications, by David Ruffieux, 2002 http://www.imec.be/esscirc/ESSCIRC2002/PDFs/C02.01.pdf http://www.imec.be/esscirc/ESSCIRC2002/presentations/Slides/C02.01.pdf ___ 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] Advantages of differential oscillator structures?
On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Advantages of differential oscillator structures?
Hi A couple of observations: 1) There are *way* more low stability oscillators out there than high stability ones. A lot of the papers are focused on applications that are not TimeNuts grade. 2) There are way more oscillator circuits out there than time to list them. Given a couple of days, you could probably invent a new circuit. 3) Most circuits you see are grounding or buffering variations of each other. Grounding / layout / component selection can be important. Some circuits are easier to layout with this or that technology. 4) There are some classic debates about add on stuff. AGC's are the best example. In loop / out of loop buffers are another. There are several others. They really don't change the basic circuit, but they do impact how it does what it does. Past that (with one exception) the world has pretty much settled on topologies that have one device as the active element. The reasoning is pretty simple - fewer active devices means less impact of active device noise and tempco. The one exception is the HP bridge circuit that Rick Karlquist came up with. There the idea is to have no active devices in the loop, with some impact on Q. There is another exception to the one active device rule, but it's not seen in precision oscillators. As you go lower in frequency, crystal loss goes up. There are cases where you simply can't get enough gain out of a practical circuit using one active device. Since you are at low frequency, the impact of the second active stage is not as great as it would be at HF. The circuit shown in the paper is one of the classic ways to get a low frequency crystal going. It's also a very simple audio square wave oscillator. The paper stuff at the links does indeed go into this issue in some detail. Bob On Aug 10, 2013, at 4:22 AM, Attila Kinali att...@kinali.ch wrote: Hi, While reading up on oscillator circuits i stumbled over differential oscillator structures (see [1] for example). But sofar i have been unable to figure out what the exact advantages of a differential oscillator strucutre in general are. Would someone here be so kind and give me some hints where to look? Thanks in advance Attila Kinali [1] A High-Stability, Ultra-Low-Power Differential Oscillator Circuit for Demanding Radio Applications, by David Ruffieux, 2002 http://www.imec.be/esscirc/ESSCIRC2002/PDFs/C02.01.pdf http://www.imec.be/esscirc/ESSCIRC2002/presentations/Slides/C02.01.pdf -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Advantages of differential oscillator structures?
Hi It's certainly a good low power approach - if you can fabricate it in silicon. I'd hate to try to do it with discrete devices. The broad band phase noise isn't going to be anything great, but that's likely not something they are worrying about in their system. Bob On Aug 10, 2013, at 9:19 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 39433ff7-ba50-4e0c-9f11-992aedcd5...@rtty.us, Bob Camp writes: A couple of observations: But you have to admit: 5) Getting into low ppm's at 1 microampere is kind of impressive... There's nothing about phase-noise, so I suspect that's where the trade-off is ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Advantages of differential oscillator structures?
In message 39433ff7-ba50-4e0c-9f11-992aedcd5...@rtty.us, Bob Camp writes: A couple of observations: But you have to admit: 5) Getting into low ppm's at 1 microampere is kind of impressive... There's nothing about phase-noise, so I suspect that's where the trade-off is ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Advantages of differential oscillator structures?
On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
Hi I think you'll find that the low current amps in their schematic have pretty large 1/f noise. Bob On Aug 10, 2013, at 11:04 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
Build it from discrete parts, of course, what frequency do you suggest to try? 32768Hz, 1MHz? I have nothing in-between... On Sat, Aug 10, 2013 at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
Hi I suspect that built from discrete parts you will simply have an audio / square wave oscillator. It's a classic multivibrator circuit…. Bob On Aug 10, 2013, at 11:13 AM, Azelio Boriani azelio.bori...@screen.it wrote: Build it from discrete parts, of course, what frequency do you suggest to try? 32768Hz, 1MHz? I have nothing in-between... On Sat, Aug 10, 2013 at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! Cheers, Magnus ___ 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 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] Advantages of differential oscillator structures?
On 08/10/2013 05:13 PM, Bob Camp wrote: Hi I think you'll find that the low current amps in their schematic have pretty large 1/f noise. True, but if you wanted to fool around a little and see what it could do. For the intended application, it's probably good enough thought. Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Bob On Aug 10, 2013, at 11:43 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:13 PM, Bob Camp wrote: Hi I think you'll find that the low current amps in their schematic have pretty large 1/f noise. True, but if you wanted to fool around a little and see what it could do. For the intended application, it's probably good enough thought. Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
Hi The stability with two active devices will be worse than with one. That's true of tc, ADEV, and phase noise. Buffering out of the circuit is problematic for a precision application, so that's likely to add to the noise as well. It's a reasonable way to do a cheap oscillator. It's probably not a lot worse than some inverter feedback clocks. It's not a great approach for a TimeNuts stable part. Bob On Aug 10, 2013, at 12:03 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? Cheers, Magnus ___ 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] Advantages of differential oscillator structures?
Hi Any bets on weather or not they have actually designed a 12.8 MHz multivibrator that injection locks to the crystal? Pretty hard with discrete parts, but not out of the question with silicon. You'd have to get their spice (or what ever) files to figure it out ... Bob On Aug 10, 2013, at 12:03 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? Cheers, Magnus ___ 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.
