On 3/14/17 12:39 PM, Attila Kinali wrote: > On Tue, 14 Mar 2017 13:39:02 +0100 > Magnus Danielson <magnus@rubidium.dyndns.org> wrote: > >> Some claims that MEMS will kill crystals. It will surely eat a good >> market share, but I think there is applications where MEMS is not mature >> enough compared to crystals. > > > The big promise of MEMS oscillators was, that they'd be cheaper (due to > integration in silicon) and used less power. As far as I am aware, > neither promise could be upheld. Well, the SiLabs parts are quite attractive for places where they are appropriate. They're cost competitive in small quantities with the "XO+PLL" modules, and physically much smaller. > > As for the demise of single quartz crystal units, I think that is not > going to happen any soon. <a few popular frequencies available in large quantities from multiple sources> I think the "individual crystal" market will remain, but it will be expensive. I fully expect that folks like Bliley and Croven (part of Wenzel since 2006) will be around for a long long time. What probably won't last much longer is companies like ICM that you could send your "frequency control module" to and have them "recrystal" it for a new frequency. The low budget folks (ham radio) will go to little synthesizer board retrofits of some sort or another - which they've already started doing, since really nice 10 MHz GPSDOs became available, rather than using that special oscillator at around 90 MHz (I can't remember the magic frequency) that you could double and triple up to microwave frequencies step by step while using your trusty 28 or 144 MHz transceiver as a back end. And some day, all those 1970s and 1980s FM repeaters still on the air 40 years later having been repurposed from land mobile radio service will be replaced by something else. My friends with a garage full of old Moto and GE gear that they've been saving just in case will have to dispose of it.

Hi, Oh yes. I remember a certain design from a certain vendor. It was an crystal oscillator, sort of. Available in many diverse frequencies (hint). It was really a crystal oscillator and a PLL that could be programmed relatively inexpensively. Solves many problems, so it's a fine product, but it is a no-go for gigabit serial links, such as fibre-channel, gigabit ethernet and the like, as the PLL caused some serious systematics. This systematics along with the noise was scaled up as the step-up PLL just did a wide-band step-up (as it should). The combination causes excessive bit-errors rendering the link quite unusefull. With the tools at my hand, a sub-sampling scope with some cool histogram capabilities I used a resistive divider and a coax delay so that I could measure the trigger point and also the 1 cycle jitter, which is essentially what dominates for this kind of setup. I could see the systematic jitter clearly this way, and I could also get numbers for the random jitter. The vendors rep said "you can't measure that!" where I insisted I could. We ended up using other products for that purpose. I ended up measuring many oscillators to approve their jitter properties. So well yes, you learn the hard way what those 4-leggers do when you have a bit of requirements. Later I dug up the patent for the process, which was focused more on the production of one standard product and late setting the frequency for customer needs. For it's purpose a great concept, not for all cases thought. I know of MEMS issues. One MEMS I measured was tossed into a lock-loop, but the noise of it made the scope-view completely smeared out, despite being locked on average. I only showed the scope, pointiing out it was locked and that was the end of that discussion. There is nothing wrong with these devices for many purposes, but expect that it may not solve everything, so measure and learn what characteristics is important for that particular application. Cheers, Magnus On 03/14/2017 04:02 PM, Bob Camp wrote: > Hi > > Some (but not all) of the resonant structures in the MEMS parts are effectively multi > resonator / multi peak structures. Because of this the phase noise has multiple major > bumps in it as you get into the region of all the peaks. Thats not going to give you > great close in phase noise or ADEV. Since the manufacturers are often a bit unclear > on “what’s inside” you need be a bit careful as you sort through the different parts out > there. Even after sorting, you still run the risk of an “improved” design suddenly > replacing the one you decided on. > > So much fun !!! > > Bob > >> On Mar 14, 2017, at 8:39 AM, Magnus Danielson <magnus@rubidium.dyndns.org> wrote: >> >> Hi, >> >> Some claims that MEMS will kill crystals. It will surely eat a good market share, but I think there is applications where MEMS is not mature enough compared to crystals. >> >> Another aspect is that various forms of synthesis technologies now exists, so that a high frequency CMOS oscillator is locked and divided down. Works sufficiently well for a whole bunch of applications. >> >> Again, your milage may vary and there is applications where you need the real deal or the right stuff. >> >> Cheers, >> Magnus >> >> >> On 03/14/2017 01:06 PM, Bob Camp wrote: >>> Hi >>> >>>> On Mar 14, 2017, at 3:19 AM, Chris Albertson <albertson.chris@gmail.com> wrote: >>>> >>>> I think what he means is that the typical device sold today has four >>>> terminals not two. It looks like a crystal because it is inside a >>>> little silver can but has four lead wires Power, ground and "output" >>>> and the fourth lead might not be used. It is an "XO" not an "X". >>>> >>>> But I argue that every one of these device has a crystal inside. So >>>> they still make crystals, just you don't see them >>> >>> These days, they may well have a MEMS resonator in them. No quartz and >>> no crystal. Good luck on the close in noise if that’s what they are doing …. >>> >>> Bob >>> >>>> >>>> On Mon, Mar 13, 2017 at 12:07 AM, Bryan _ <bpl521@outlook.com> wrote: >>>>> sorry, what do you mean by "complete oscillator" have outnumbered loose crystals? >>>>> >>>>> >>>>> -=Bryan=- >>>>> >>>>> >>>>> ________________________________ >>>>> From: time-nuts <time-nuts-bounces@febo.com> on behalf of Richard (Rick) Karlquist <richard@karlquist.com> >>>>> Sent: March 12, 2017 4:38 PM >>>>> To: Discussion of precise time and frequency measurement >>>>> Subject: Re: [time-nuts] Bye-Bye Crystals >>>>> >>>>> I got a job in 1975 to design Konel's first synthesized radio, which >>>>> was to obsolete their crystal controlled radios. That's over 40 years >>>>> ago. The other trend (not mentioned) is that since 20 years ago or >>>>> so, complete oscillator sales have vastly outnumbered sales of loose >>>>> crystals. >>>>> >>>>> Rick N6RK >>>>> >>>>> On 3/11/2017 8:51 PM, Bob Camp wrote: >>>>>> Hi >>>>>> >>>>>> International’s main business was re-channeling non-synthesized radios and replacing >>>>>> broken crystals in various pieces of com gear. It’s been a *lot* of years since the last of the >>>>>> non-synthesized radios came out. The business probably has been dropping off pretty steadily >>>>>> for many years … >>>>>> >>>>>> Bob >>>>>> >>>>>>> On Mar 11, 2017, at 10:39 PM, jimlux <jimlux@earthlink.net> wrote: >>>>>>> >>>>>>> On 3/11/17 4:30 PM, Scott McGrath wrote: >>>>>>>> From the tone of the letter it sounds like the bank cancelled line of credit, >>>>>>> >>>>>>> Or, he wants to retire and nobody wants to carry it on. His dad started it in 1950, the son picked it up in 1970. It's 47 years later. >>>>>>> >>>>>>>> >>>>>>>> Which is stupid given that much of their line is military which is getting a huge boost in spending >>>>>>> >>>>>>> Plenty of other crystal and oscillator manufacturers around. >>>>>>> >>>>>>> There's also a change in what kinds of crystals are needed. I suspect most things being built and designed today use the crystal as a "master oscillator" that is used to drive some sort of synthesis chain. The need for "I have to have a 12.345,324 Hz crystal" is going away. >>>>>>> >>>>>>> >>>>>>>> >>>>>>>>> On Mar 11, 2017, at 4:56 PM, Bryan _ <bpl521@outlook.com> wrote: >>>>>>>>> >>>>>>>>> Disappearing or manufacturing just moving overseas?. Video at the bottom is interesting, classic. >>>>>>>>> >>>>>>>>> >>>>>>>>> http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/ >>>>> [https://www.bing.com/th?id=OVF.LElrlkkbByR3K%2f6qfaeHjg&pid=Api]<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/> >>>>> >>>>> So Long, and Thanks for all the Crystals<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/> >>>>> hackaday.com >>>>> There was a time when anyone involved with radio transmitting -- ham operators, CB'ers, scanner enthusiasts, or remote control model fans -- had a collection of ... >>>>> >>>>> >>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> -=Bryan=- >>>>>>>>> _______________________________________________ >>>>>>>>> time-nuts mailing list -- time-nuts@febo.com >>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >>>>> www.febo.com >>>>> time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... >>>>> >>>>> >>>>> >>>>>>>>> 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 >>>>> time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >>>>> www.febo.com >>>>> time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... >>>>> >>>>> >>>>> >>>>>>>> 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 >>>>> time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >>>>> www.febo.com >>>>> time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... >>>>> >>>>> >>>>> >>>>>>> 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 >>>>> time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >>>>> www.febo.com >>>>> time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... >>>>> >>>>> >>>>> >>>>>> 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. >>>> >>>> >>>> >>>> -- >>>> >>>> Chris Albertson >>>> Redondo Beach, California >>>> _______________________________________________ >>>> 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 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. >

Attila, On 03/14/2017 08:39 PM, Attila Kinali wrote: > On Tue, 14 Mar 2017 13:39:02 +0100 > Magnus Danielson <magnus@rubidium.dyndns.org> wrote: > >> Some claims that MEMS will kill crystals. It will surely eat a good >> market share, but I think there is applications where MEMS is not mature >> enough compared to crystals. > > MEMS is quite mature, it's just that it is playing a different game. > While with quartz (and other piezoelectric crystals) we know how > to design a crystal to frequency, things aren't so simple for MEMS. > Simply scaling the design doesn't work apparently. > > What they instead do is to use the MEMS oscillator as a reference > for a PLL locked VCO. As the whole thing is going to be a few mm^2 > of silicon anyways, reserving some µm^2 for the PLL and VCO don't > cost much. And it gives the ability to "tune" the oscillator > for the frequency needed after production (the same technique is used > with "programmable" crystal oscillators). Of course, having a PLL, > mostly a fractional-N PLL, causes a lot of spurs in the output, > which can cause problems, depending on the application. Actually, as I described in a post before, all this actually started with crystal oscillators and was motivated by much simplified production as a fixed crystal frequency could be manufactured and then resynthesized to any of a large set of frequencies much later. When MEMS came along, the whole pipe was already cleaned and "a minor implementation detail" could be changed. > The big promise of MEMS oscillators was, that they'd be cheaper (due to > integration in silicon) and used less power. As far as I am aware, > neither promise could be upheld. MEMS need a quite different production > process than normal digital electronics, hence it's usually more economic > to have the oscillator on a different die than the digital chip. As for > power consumption, the low power MEMS are about at the same level as the > low power 32kHz crystal oscillators (and also in the same frequency). > One place where MEMS are exceedingly good is temperature characteristics. > Silabs demonstrated an oscillator, which, prior to any compensation, > exhibited only <5ppm shift over the full temperature range. For many purposes, I see MEMS as a nice complementary technology. The market cut and splices up a bit differently between them than it used to be, but not very drastic. > As for the demise of single quartz crystal units, I think that is not > going to happen any soon. It is rather that the economics shift. Most > of the single crystals are used as reference oscillators for digital > and analog/RF chips. Ie most these chips have an internal oscillator > that uses an external crystal to drive their internall VCO+PLL. > As the crystal frequency is dictated by the frequencies these chips > have to generate, there is a kind of standardization going on due to > the limited number of protocols that need special frequencies. Two very > common frequencies are 12MHz, for USB, and 25MHz, for Ethernet. > 16MHz is base for CAN, some Wifi chipsets and USB as well. Then there > are a couple of frequencies that are related to GSM, UMTS and the various > other telephone standards. There are maybe a handfull of these frequencies, > which "everyone" needs (ie are used in many high volume products). These are > the crystals we will be able around for the forseeable future. There are > other frequencies that are less used, which you will still get, but need > to pay more or are made to order. Frequencies for protocols that are > not used much anymore, or can be easily generated from another frequency > that is more common, are bound to die out (as has happend with all those > UART crystals, which are only used in legacy systems or for historical reasons). In general, the miniatyrization of synthesis is a much greater change to the scenery than MEMS. There is plenty of chips out there that allows you to synthesize several frequencies. A re-occurring structure is a high-frequency CMOS oscillator, possibly multi-phase, which is locked to a reference (say 20 MHz or 26 MHz) and then output dividers provide variants. Fractional synthesis is also in there for more uneven frequency shifts. FPGAs also comes which multiple DLLs and lately PLLs on chip that does essentially the same thing, but maybe not as elaborate as the dedicated chips. DDS chips is another branch. In general, these types of chips have become much much better in terms of jitter, frequency range, control etc. In this context, MEMS does much less to affect the market. The whole synthesiz part have made huge difference for a whole range of products already. > For specialized applications, where the crystal is not directly interfaced > to a chip that provides the oscillator, it is more convenient for the > designer to just use a complete oscillator than to design his own oscillator > with all the problems that it involves. Getting such a device reliable to > work in production volumes is nothing an average engineer without prior > experience in can just pull off. Heck, I design my stuff to use oscialltors > instead of crystals, because that's one thing less I have to care about. > But even with these oscillators, there is only a limited number of frequencies > that are easy to get. Those are again the standard frequencies from above, > and a couple of round numbers (like multiples of 10MHz) There is a number of more or less odd-ball frequences that occur. For instance, 25 MHz isn't used as much as 125 MHz these days for Ethernet, as it matches the needs of GE. 148,5 MHz is another, in that range there is a number of numbers that fit various gigabit-pipes divided by numbers like 10, 16, 20, 32, 64, 66 and such. SAW oscillators is another approach used there. Cheers, Magnus

On 3/14/17 3:17 PM, Magnus Danielson wrote: > > > So well yes, you learn the hard way what those 4-leggers do when you > have a bit of requirements. Later I dug up the patent for the process, > which was focused more on the production of one standard product and > late setting the frequency for customer needs. For it's purpose a great > concept, not for all cases thought. > actually, we use a lot of them in breadboards where you want to get "cycle accurate" timing from FPGA logic at oddball clock rates when developing software. Historically, deep space radios have had a crystal that is related to the assigned deep space channel number. This would be referred to as the f0 (f-naught) frequency and is around 9-10 MHz. So if your assigned channel was 14, and your S-band downlink is at 2295.000000, you'd have a VCXO crystal cut for f0=9.5625 MHz (240xf0). Your uplink frequency would be 2113.3125 or 221*f0. The receiver LO would be 220*f0, the IF at f0, and you'd set your VCXO PLL to lock to the received IF. If you work all the multipliers and such carefully, all the drifts and noises mostly cancel out. If you had a different channel assignment, you'd have a different crystal. Same for X-band, except the ratio is 880/749 It took 2-3 years to get the crystal, but you're applying for your frequency allocation years before anyway. These days, the oscillator runs at 4*f0 or 8*f0. In any case, when we started using digital tracking loops, you'd run the ADC and DAC at the same f0, and the FPGA at that same f0 (or some multiple, like 76.5 MHz). Similarly, for near earth comm, they use PN spreading codes at around 3 MHz where the chip rate is a integer fraction of the carrier frequency (just like GPS), and it's convenient to have the DACs running at an exact multiple of the chip rate, so you have an even number of samples/chip. The GPS folks like a frequency that's something like 48.xxx MHz, because sampling at that rate makes all the signals alias down to somewhere convenient even at max negative Doppler. Then you have a microprocessor that might be running at some other convenient speed (like 66 MHz). Since it takes years go get your crystal (and what if you want to re-use the breadboard for another mission on a different channel) it's handy to have a plug in oscillator at the "right" frequency- yeah, it's got a lot of jitter, but at least you can do things like test the logic behavior for all possible values of register settings and stuff like that, which would be impractical with the simulator which runs very, very slowly compared to real time. The other reason we might run at something like 45 MHz is that it allows us to use a converter rated at 50 MHz without having to explain why we're running right at the rated speed with no design margin. Woe to the poor guy or gal, though who starts to run bit error rate tests on the RF generated from these convenient devices. BTW, there are two spacecraft at Mars with the same channel number.. because one of them used the spare radio from the previous mission - if you have dual redundancy, and a project with a nice budget, you buy three radios. Then, when you've launched, that spare can be adopted by a subsequent mission, so you might wind up with a spacecraft with prime and redundant on different channels (a pain in test and operationally), and yet another channel in the testbed. Our newer designs use DDS synthesis, so we're going to standard clock frequencies like 50 or 80 or 100 MHz. For missions doing radio science that carry a USO, all this same stuff about getting the frequency right also counts (most of our radios have an "ext ref" input for this purpose). ANd for the same "what if the channel changes" reason, Applied Physics Lab (who make USOs) has a uso design with a DDS in it. Both we and APL (and I imagine anyone else in this limited business area, like Thales) have spent some time working on DDS designs with "good" spur behavior, but overall, having a radio that tunes the entire band is a good thing. Today, I'd build a radio with a reference oscillator at a "nice frequency" (probably 100 MHz), multiply that up for a block converter, then digitize the entire band (or maybe a chunk) (X-band is only 50 MHz wide, Ka-band is 500 MHz wide) and do the carrier recovery and tracking entirely in digital.

On 3/14/17 3:49 PM, Magnus Danielson wrote: > There is a number of more or less odd-ball frequences that occur. For > instance, 25 MHz isn't used as much as 125 MHz these days for Ethernet, > as it matches the needs of GE. 148,5 MHz is another, in that range there > is a number of numbers that fit various gigabit-pipes divided by numbers > like 10, 16, 20, 32, 64, 66 and such. SAW oscillators is another > approach used there. > I would suggest we look to our Babylonian forebears and choose 360 as the mother of all frequencies. Just because we have ten fingers and ten toes is no reason to be slaves to frequencies like 10 or 100 MHz. Cast off the shackles deriving from Roman counting.