Forums

dual gate mosfet oscillator

Started by bitrex March 26, 2014
 
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?

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 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. -- ----Android NewsGroup Reader---- http://www.piaohong.tk/newsgroup
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
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. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
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.
BF1210 comes up as "discontinued". ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
>> What part did you have in mind? 3 volts sounds low for a dual-gate.
>NXP seems to make several with a 6 v drain to source breakdown > (BF1210?) that look like they could work.
Past the last-buy date on that one. "No replacement." I wonder whether they'd been asked to produce this sort of specialized device for a particular customer's special application, tried to commercialize it, and found that there wasn't sufficient demand to make it worth keeping the part active? The BF1105R is still made (Mouser and Future have them in stock). 7-volt minimum D-S breakdown voltage, with a gate2-source threshold voltage of around 0.8 when gate-1 is at 5 volts. At $0.39 each (Mouser onesies price) it seems like an experiment would be practical :-) Maybe use a Schottky diode output level detector to feed back to the upper gate bias?
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? Some circuits in that range use a VCO operating at a high frequency, phase-locked to a lower frequency crystal oscillator. Fred
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? > >Some circuits in that range use a VCO operating at a high frequency, >phase-locked to a lower frequency crystal oscillator. > >Fred
I know that there are "mesa-etched" crystals above 100MHz, but I haven't seen one as high as 500MHz. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
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 -- 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 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 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