On Wed, 26 Mar 2014 16:51:12 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 03/26/2014 03:32 AM, bitrex wrote: >> >> Anyone have any experience with how dual gate mosfets perform in >> a crystal oscillator role, at low voltages (< 3 v), at >> frequencies say 200 - 500 MHz? >> > >Probably noisy. Plus their f_max is usually around 700 MHz, so they >don't have a lot of gain up there, which is a problem with high overtone >crystals. (Or are you using one of the fancy-schmance high fundamental >ones?) > >Cheers > >Phil HobbsIt's pretty much not worth building your own XOs these days. Packaged oscillators are so good and cheap. Some of the synthetic oscillators, like the Fox Xpresso and the Silabs parts, go to really high frequencies and are cheaper than you can buy the parts to make an oscillator. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
dual gate mosfet oscillator
Started by ●March 26, 2014
Reply by ●March 26, 20142014-03-26
Reply by ●March 26, 20142014-03-26
On Wed, 26 Mar 2014 18:03:29 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 03/26/2014 11:38 AM, John Larkin wrote: >> On Wed, 26 Mar 2014 09:38:46 +0000 (GMT), bitrex <bitrex@de.lete.earthlink.net> >> wrote: >> >>> John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> Wrote in >>> message: >>>> On Wed, 26 Mar 2014 07:32:03 +0000 (GMT), bitrex <bitrex@de.lete.earthlink.net> >>>> wrote: >>>> >>>>> Anyone have any experience with how dual gate mosfets perform in >>>>> a crystal oscillator role, at low voltages (< 3 v), at >>>>> frequencies say 200 - 500 MHz? >>>> >>>> What part did you have in mind? 3 volts sounds low for a dual-gate. >>>> >>>> >>>> -- >>>> >>>> John Larkin Highland Technology Inc >>>> www.highlandtechnology.com jlarkin at highlandtechnology dot com >>>> >>>> Precision electronic instrumentation >>>> >>> >>> NXP seems to make several with a 6 v drain to source breakdown >>> (BF1210?) that look like they could work. >> >> Wow, that's a strange part. They don't say what's inside. >> >> > >Looks like a long tail pair with the G2s connected together. You >normally bypass those to ground anyway, so it might work pretty well for >some things. > >Cheers > >Phil HobbsIt's asymmetric, and G2 draws current. Good thing it's obsolete. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 27, 20142014-03-27
On Wed, 26 Mar 2014 16:04:35 -0400, Fred McKenzie <fmmck@aol.com> wrote:>In article <E_adnTWFNK9GVK_OnZ2dnUVZ_qGdnZ2d@earthlink.com>, > bitrex <bitrex@de.lete.earthlink.net> wrote: > >> Anyone have any experience with how dual gate mosfets perform in >> a crystal oscillator role, at low voltages (< 3 v), at >> frequencies say 200 - 500 MHz? > >Do you mean an oscillator that works with a 200 - 500 MHz crystal? Are >there such crystals?Two decades ago, the highest frequency I had seen was a 116 MHz 5th overtone crystal, but as far as I understand a lot higher frequencies are currently available. With overtone crystals, you need a tank (LC) circuit at the required frequency, otherwise the crystal might oscillate at the fundamental frequency :-).
Reply by ●March 27, 20142014-03-27
On a sunny day (Thu, 27 Mar 2014 09:13:24 +0200) it happened upsidedown@downunder.com wrote in <blj7j996e0a6i6812lbrjd7n555dj58akh@4ax.com>:>On Wed, 26 Mar 2014 16:04:35 -0400, Fred McKenzie <fmmck@aol.com> >wrote: > >>In article <E_adnTWFNK9GVK_OnZ2dnUVZ_qGdnZ2d@earthlink.com>, >> bitrex <bitrex@de.lete.earthlink.net> wrote: >> >>> Anyone have any experience with how dual gate mosfets perform in >>> a crystal oscillator role, at low voltages (< 3 v), at >>> frequencies say 200 - 500 MHz? >> >>Do you mean an oscillator that works with a 200 - 500 MHz crystal? Are >>there such crystals? > >Two decades ago, the highest frequency I had seen was a 116 MHz 5th >overtone crystal, but as far as I understand a lot higher frequencies >are currently available. > >With overtone crystals, you need a tank (LC) circuit at the required >frequency, otherwise the crystal might oscillate at the fundamental >frequency :-).I bought a bunch of 100 MHz oscillator modules from ebay... ebay item 261003544995 6 for 9$ free shipping, cannot make it for that... logic output, works great. At that price I would think 200 MHz must exist too:-) And sure enough: ebay 261319059458 4$49 200 MHz US And that was a 5 second search.
Reply by ●March 28, 20142014-03-28
John Larkin <jlarkin@highlandtechnology.com> Wrote in message:> On Wed, 26 Mar 2014 16:51:12 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>On 03/26/2014 03:32 AM, bitrex wrote: >>> >>> Anyone have any experience with how dual gate mosfets perform in >>> a crystal oscillator role, at low voltages (< 3 v), at >>> frequencies say 200 - 500 MHz? >>> >> >>Probably noisy. Plus their f_max is usually around 700 MHz, so they >>don't have a lot of gain up there, which is a problem with high overtone >>crystals. (Or are you using one of the fancy-schmance high fundamental >>ones?) >> >>Cheers >> >>Phil Hobbs > > It's pretty much not worth building your own XOs these days. Packaged > oscillators are so good and cheap. > > Some of the synthetic oscillators, like the Fox Xpresso and the Silabs > parts, go to really high frequencies and are cheaper than you can buy > the parts to make an oscillator. > > > -- > > John Larkin Highland Technology, Inc > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com > >Don't those oscillator modules usually require a supply voltage of 3.3 to 5 volts to work, though? -- ----Android NewsGroup Reader---- http://www.piaohong.tk/newsgroup
Reply by ●March 28, 20142014-03-28
John Larkin <jlarkin@highlandtechnology.com> Wrote in message:> On Wed, 26 Mar 2014 16:51:12 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>On 03/26/2014 03:32 AM, bitrex wrote: >>> >>> Anyone have any experience with how dual gate mosfets perform in >>> a crystal oscillator role, at low voltages (< 3 v), at >>> frequencies say 200 - 500 MHz? >>> >> >>Probably noisy. Plus their f_max is usually around 700 MHz, so they >>don't have a lot of gain up there, which is a problem with high overtone >>crystals. (Or are you using one of the fancy-schmance high fundamental >>ones?) >> >>Cheers >> >>Phil Hobbs > > It's pretty much not worth building your own XOs these days. Packaged > oscillators are so good and cheap. > > Some of the synthetic oscillators, like the Fox Xpresso and the Silabs > parts, go to really high frequencies and are cheaper than you can buy > the parts to make an oscillator. > > > -- > > John Larkin Highland Technology, Inc > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com > >I looked at Mouser for the silabs parts...for a 500 MHz module they wanted 40 bucks, and it needed 3.3 volts...and it was non stock. :( -- ----Android NewsGroup Reader---- http://www.piaohong.tk/newsgroup
Reply by ●March 28, 20142014-03-28
On Thursday, March 27, 2014 12:46:57 AM UTC-7, Jan Panteltje wrote:> On a sunny day (Thu, 27 Mar 2014 09:13:24 +0200) it happened > > upsidedown@downunder.com wrote in > > <blj7j996e0a6i6812lbrjd7n555dj58akh@4ax.com>:> I bought a bunch of 100 MHz oscillator modules from ebay...> At that price I would think 200 MHz must exist too:-) > > And sure enough: > > ebay 261319059458 > > 4$49 200 MHz USOscillator modules, of course, come in lots of varieties; some are PLL and locked to a quartz crystal well below the output frequency; it isn't just small-integer-multiple 'overtone' tricks that are in these modules! See <http://www.silabs.com/Support%20Documents/TechnicalDocs/SI530.pdf>
Reply by ●March 28, 20142014-03-28
On a sunny day (Fri, 28 Mar 2014 03:28:29 -0700 (PDT)) it happened whit3rd <whit3rd@gmail.com> wrote in <ec3d7829-dfd2-43fe-8673-7304e39e0424@googlegroups.com>:>On Thursday, March 27, 2014 12:46:57 AM UTC-7, Jan Panteltje wrote: >> On a sunny day (Thu, 27 Mar 2014 09:13:24 +0200) it happened >> >> upsidedown@downunder.com wrote in >> >> <blj7j996e0a6i6812lbrjd7n555dj58akh@4ax.com>: > >> I bought a bunch of 100 MHz oscillator modules from ebay... > > >> At that price I would think 200 MHz must exist too:-) >> >> And sure enough: >> >> ebay 261319059458 >> >> 4$49 200 MHz US > >Oscillator modules, of course, come in lots of varieties; some >are PLL and locked to a quartz crystal well below the output >frequency; it isn't just small-integer-multiple 'overtone' tricks that >are in these modules! >See <http://www.silabs.com/Support%20Documents/TechnicalDocs/SI530.pdf>Right and who cares what is in it as long as it meets specs.
Reply by ●March 28, 20142014-03-28
On 3/28/2014 6:38 AM, Jan Panteltje wrote:> On a sunny day (Fri, 28 Mar 2014 03:28:29 -0700 (PDT)) it happened whit3rd > <whit3rd@gmail.com> wrote in > <ec3d7829-dfd2-43fe-8673-7304e39e0424@googlegroups.com>: > >> On Thursday, March 27, 2014 12:46:57 AM UTC-7, Jan Panteltje wrote: >>> On a sunny day (Thu, 27 Mar 2014 09:13:24 +0200) it happened >>> >>> upsidedown@downunder.com wrote in >>> >>> <blj7j996e0a6i6812lbrjd7n555dj58akh@4ax.com>: >> >>> I bought a bunch of 100 MHz oscillator modules from ebay... >> >> >>> At that price I would think 200 MHz must exist too:-) >>> >>> And sure enough: >>> >>> ebay 261319059458 >>> >>> 4$49 200 MHz US >> >> Oscillator modules, of course, come in lots of varieties; some >> are PLL and locked to a quartz crystal well below the output >> frequency; it isn't just small-integer-multiple 'overtone' tricks that >> are in these modules! >> See <http://www.silabs.com/Support%20Documents/TechnicalDocs/SI530.pdf> > > Right and who cares what is in it as long as it meets specs. >The phase noise of some of those synthesized modules has to be seen to be believed. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●March 28, 20142014-03-28
On a sunny day (Fri, 28 Mar 2014 08:38:58 -0400) it happened Phil Hobbs <hobbs@electrooptical.net> wrote in <53356D62.5030804@electrooptical.net>:>On 3/28/2014 6:38 AM, Jan Panteltje wrote: >> On a sunny day (Fri, 28 Mar 2014 03:28:29 -0700 (PDT)) it happened whit3rd >> <whit3rd@gmail.com> wrote in >> <ec3d7829-dfd2-43fe-8673-7304e39e0424@googlegroups.com>: >> >>> On Thursday, March 27, 2014 12:46:57 AM UTC-7, Jan Panteltje wrote: >>>> On a sunny day (Thu, 27 Mar 2014 09:13:24 +0200) it happened >>>> >>>> upsidedown@downunder.com wrote in >>>> >>>> <blj7j996e0a6i6812lbrjd7n555dj58akh@4ax.com>: >>> >>>> I bought a bunch of 100 MHz oscillator modules from ebay... >>> >>> >>>> At that price I would think 200 MHz must exist too:-) >>>> >>>> And sure enough: >>>> >>>> ebay 261319059458 >>>> >>>> 4$49 200 MHz US >>> >>> Oscillator modules, of course, come in lots of varieties; some >>> are PLL and locked to a quartz crystal well below the output >>> frequency; it isn't just small-integer-multiple 'overtone' tricks that >>> are in these modules! >>> See <http://www.silabs.com/Support%20Documents/TechnicalDocs/SI530.pdf> >> >> Right and who cares what is in it as long as it meets specs. >> > >The phase noise of some of those synthesized modules has to be seen to >be believed.That pdf says: Parameter Symbol Test Condition Min Typ Max Unit Phase Jitter (RMS)1 J 12 kHz to 20 MHz (OC-48) -- 0.25 0.40 ps for FOUT > 500 MHz 50 kHz to 80 MHz (OC-192) -- 0.26 0.37 ps Phase Jitter (RMS)1 J 12 kHz to 20 MHz (OC-48) -- 0.36 0.50 ps for FOUT of 125 to 500 MHz 50 kHz to 80 MHz (OC-192)2 -- 0.34 0.42 ps Phase Jitter (RMS) J 12 kHz to 20 MHz (OC-48)2 -- 0.62 -- ps for FOUT of 10 to 160 MHz CMOS Output Only 50 kHz to 20 MHz2 -- 0.61 -- ps Notes: 1. Refer to AN256 for further information. BTW the 100 MHz from ebay is direct I think, I use it the DVB-S modulator, and the constellation is very stable, mm and a free running VCO on top of that to mix it up. But I do not have the nice equipment to check it with that you have, only this: http://panteltje.com/panteltje/raspberry_pi_dvb-s_transmitter/xdipo_locked_to_raspberry_pi_datv_transmitter_IMG_3938.JPG The pictjure looks good, :-) Sure, synthesized, I dunnit with FPGA as I posted here for GPS generation... bit of low-pass to drive the VCO, no problem.
