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dual gate mosfet oscillator

Started by bitrex March 26, 2014
On 03/28/2014 10:46 AM, Jan Panteltje wrote:
> 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.
Any idea what bandwidth that's in? DC to 100 MHz->good, 1 Hz bad. 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
On a sunny day (Fri, 28 Mar 2014 10:21:47 +0000 (GMT)) it happened bitrex
<bitrex@de.lete.earthlink.net> wrote in
<lImdnUyYI885CajOnZ2dnUVZ_rmdnZ2d@earthlink.com>:

>> 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 >> >> > >Ilooked 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. :(
If you have an FPGA on board, it is easy to make your own: http://panteltje.com/pub/GPS_L1_locked_to_rubidium_reference_test_setup_IMG_3733.GIF Is 1575420000 high enough? From 10 MHz rubidium that is, in 2 steps. Step 1 was this: http://panteltje.com/pub/FPGA_board_with_25MHz_VCXO_locked_to_rubidium_10MHz_reference_IMG_3724.GIF
wrote in message news: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 :-).
And it can get quite tricky. Depending on type, there is a very close unwarranted mode. e.g. a 35MHz fundamental, with 100MHz desired OT, with an unwanted 110MHz. A mode trap of a series LC with a parallel cap all in series with the xtal is usually used to knock it out. A resister across the xtal can often be used to reject the fundamental by way of phase change. Regards Kevin Aylward B.Sc. kevin@kevinaylward.co.uk www.kevinaylward.co.uk