Reply by Phil Hobbs February 24, 20142014-02-24
On 2/24/2014 9:16 AM, George Herold wrote:
> On Saturday, February 22, 2014 1:59:20 AM UTC-5, > upsid...@downunder.com wrote: >> On Fri, 21 Feb 2014 22:02:09 -0800, John Larkin >> >> <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Fri, 21 Feb 2014 23:03:49 +0200, upsidedown@downunder.com >>> wrote: >>> >>>> On Fri, 21 Feb 2014 12:00:28 -0800 (PST), George Herold >> >>>> <gherold@teachspin.com> wrote: >> >>>> >> >>>>> Hi guys, The 200 MHz. frequency synthesizer thread got me >>>>> thinking. >> >>>>> I could use a 200MHz VFO (say 150 to 250 MHz or something >>>>> like that) >>>> >>>> That is a quite broad range +/-25 % >>>> >>> >>> There are lot of octave-range VCOs on the market, maybe just a >>> tad more. >> Unfortunately a large tuning range also means extreme sensitivity >> to VCO control voltage fluctuations. >> >> To get to the 1000 ppm requirement by the OP, the VCO control >> voltage must be clean to a few mV. > OK I think I should be able to make the VCO control voltage stable at > the mV level. I don't really need such a big range. But if I go the > minicircuits route I'm stuck with whatever varactor they put in > there. > > George H.
Cleaning it up with an RC lowpass isn't very hard--that's what's inside the MCL VCO. Cheers Phil Hobbs
Reply by Jim Thompson February 24, 20142014-02-24
On Mon, 24 Feb 2014 06:21:29 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Sunday, February 23, 2014 12:03:21 PM UTC-5, Jim Thompson wrote: >> On Fri, 21 Feb 2014 12:00:28 -0800 (PST), George Herold >> >> <gherold@teachspin.com> wrote: >> >> >> >> >Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. >> >> >I could use a 200MHz VFO (say 150 to 250 MHz or something like that) >> >> >I don't need much stability, a part per thousand for a several minutes would be enough. >> >> >So what's the simplest way to get there? An LC oscillator (I've got some nice tunable few pF caps) >> >> >There's also a VCO from Maxim. (max2607) that looks easy. >> >> >http://datasheets.maximintegrated.com/en/ds/MAX2605-MAX2609.pdf >> >> >Would the manually tunable cap be more stable than the VCO? >> >> > >> >> >Thanks, >> >> >George H. >> >> My old original... >> >> <http://www.analog-innovations.com/SED/MC1648-DataSheet.pdf> >> > >OK Thanks Jim, I think I may spend money and save time by just getting >a minicircuits thing.
Certainly. Hard to beat someone putting it all in one package for you.
> >George H. >> will do that. However I believe there's now a 12000 series ECL/PECL >> equivalent that will go even faster. >>
[snip] ...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.
Reply by George Herold February 24, 20142014-02-24
On Sunday, February 23, 2014 12:03:21 PM UTC-5, Jim Thompson wrote:
> On Fri, 21 Feb 2014 12:00:28 -0800 (PST), George Herold > > <gherold@teachspin.com> wrote: > > > > >Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. > > >I could use a 200MHz VFO (say 150 to 250 MHz or something like that) > > >I don't need much stability, a part per thousand for a several minutes would be enough. > > >So what's the simplest way to get there? An LC oscillator (I've got some nice tunable few pF caps) > > >There's also a VCO from Maxim. (max2607) that looks easy. > > >http://datasheets.maximintegrated.com/en/ds/MAX2605-MAX2609.pdf > > >Would the manually tunable cap be more stable than the VCO? > > > > > >Thanks, > > >George H. > > My old original... > > <http://www.analog-innovations.com/SED/MC1648-DataSheet.pdf> >
OK Thanks Jim, I think I may spend money and save time by just getting a minicircuits thing. George H.
> will do that. However I believe there's now a 12000 series ECL/PECL > equivalent that will go even faster. > > > > ...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.
Reply by George Herold February 24, 20142014-02-24
On Saturday, February 22, 2014 1:59:20 AM UTC-5, upsid...@downunder.com wrote:
> On Fri, 21 Feb 2014 22:02:09 -0800, John Larkin > > <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > > >On Fri, 21 Feb 2014 23:03:49 +0200, upsidedown@downunder.com wrote: > > > >>On Fri, 21 Feb 2014 12:00:28 -0800 (PST), George Herold > > >><gherold@teachspin.com> wrote: > > >> > > >>>Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. > > >>>I could use a 200MHz VFO (say 150 to 250 MHz or something like that) > >> > >>That is a quite broad range +/-25 % > >> > > > >There are lot of octave-range VCOs on the market, maybe just a tad more. > Unfortunately a large tuning range also means extreme sensitivity to > VCO control voltage fluctuations. > > To get to the 1000 ppm requirement by the OP, the VCO control voltage > must be clean to a few mV.
OK I think I should be able to make the VCO control voltage stable at the mV level. I don't really need such a big range. But if I go the minicircuits route I'm stuck with whatever varactor they put in there. George H.
> > > > I have seen far too many radios with PLL (and hence VCO) in which > > dirty control line voltage is causing severe phase noise and as a > > consequence other bad things, like reciprocal mixing.
Reply by George Herold February 24, 20142014-02-24
On Friday, February 21, 2014 7:01:20 PM UTC-5, bloggs.fred...@gmail.com wrote:
> On Friday, February 21, 2014 3:00:28 PM UTC-5, George Herold wrote: > > > Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. > > > > > > I could use a 200MHz VFO (say 150 to 250 MHz or something like that) > > > > > > I don't need much stability, a part per thousand for a several minutes would be enough. > > > > > > So what's the simplest way to get there? An LC oscillator (I've got some nice tunable few pF caps) > > > > > > There's also a VCO from Maxim. (max2607) that looks easy. > > > > > > http://datasheets.maximintegrated.com/en/ds/MAX2605-MAX2609.pdf > > > > > > Would the manually tunable cap be more stable than the VCO? > > > > > > > > > > > > Thanks, > > > > > > George H. > > > > These things are cheap and way better than anything you can make. They're hard to beat even in volume: > > http://www.minicircuits.com/products/Oscillators.shtml
Thanks Fred, (and others) I think mini circuits may be the answer. I'll order one to play with. George H.
Reply by Jim Thompson February 23, 20142014-02-23
On Fri, 21 Feb 2014 12:00:28 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. >I could use a 200MHz VFO (say 150 to 250 MHz or something like that) >I don't need much stability, a part per thousand for a several minutes would be enough. >So what's the simplest way to get there? An LC oscillator (I've got some nice tunable few pF caps) >There's also a VCO from Maxim. (max2607) that looks easy. >http://datasheets.maximintegrated.com/en/ds/MAX2605-MAX2609.pdf >Would the manually tunable cap be more stable than the VCO? > >Thanks, >George H.
My old original... <http://www.analog-innovations.com/SED/MC1648-DataSheet.pdf> will do that. However I believe there's now a 12000 series ECL/PECL equivalent that will go even faster. ...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.
Reply by Tim Wescott February 23, 20142014-02-23
On Fri, 21 Feb 2014 16:04:22 -0800, bloggs.fredbloggs.fred wrote:

> On Friday, February 21, 2014 5:56:10 PM UTC-5, Joerg wrote: > > >> >> What some of the Chinese vendors do is copy an example design from a >> >> datasheet or app note, verbatim. It seems to work. > > Many times the datasheet or app note is the circuit the device > manufacturer developed under contract to an end user. So there's no > "seems to work" to it.
I worked for a guy once who did circuit design by tossing together a salad of circuits from data sheets, with no attention paid to grounding or impedance matching issues (or for keeping quiet circuits away from noisy ones, for that matter). "Seems to work" was a pretty good summation of what he got, and was part of why he hired me. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
Reply by John Fields February 22, 20142014-02-22
On Sat, 22 Feb 2014 09:09:32 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Sat, 22 Feb 2014 08:59:20 +0200, upsidedown@downunder.com wrote: > >>On Fri, 21 Feb 2014 22:02:09 -0800, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Fri, 21 Feb 2014 23:03:49 +0200, upsidedown@downunder.com wrote: >>> >>>>On Fri, 21 Feb 2014 12:00:28 -0800 (PST), George Herold >>>><gherold@teachspin.com> wrote: >>>> >>>>>Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. >>>>>I could use a 200MHz VFO (say 150 to 250 MHz or something like that) >>>> >>>>That is a quite broad range +/-25 % >>>> >>> >>>There are lot of octave-range VCOs on the market, maybe just a tad more. >> >>Unfortunately a large tuning range also means extreme sensitivity to >>VCO control voltage fluctuations. > >I wouldn't have it any other way.
--- God wouldn't have it any other way; you're just along for the ride.
Reply by February 22, 20142014-02-22
On Saturday, February 22, 2014 10:37:53 AM UTC-5, Joerg wrote:
> upsidedown@downunder.com wrote: > > > On Fri, 21 Feb 2014 16:04:22 -0800 (PST), > > > bloggs.fredbloggs.fred@gmail.com wrote: > > > > > >> On Friday, February 21, 2014 5:56:10 PM UTC-5, Joerg wrote: > > >> > > >>> > > >>> What some of the Chinese vendors do is copy an example design from a > > >>> > > >>> datasheet or app note, verbatim. It seems to work. > > >> Many times the datasheet or app note is the circuit the device manufacturer developed under contract to an end user. So there's no "seems to work" to it. > > > > > > However, in many cases a recently hired engineer is set to write these > > > application notes to familiarize with company products :-) > > > > > > > I have experienced exactly such examples. The first one right after > > getting my degree. Due to my hobby I could hit the ground running but > > that was not at all the case for most of the mates there. Most could > > solve anything back to the Maxwell equations, strictly on paper, but not > > even repair their own TV set. By chance I met one of them during a > > business trip. "Hey, how's it going? Where did you end up?" I asked. > > "Oh, I started at [insert major semiconductor manufacturer here]" ... > > "Interesting. So what are you doing there?" ... "Writing application > > notes". I could not believe it. > > > > -- > > Regards, Joerg > > > > http://www.analogconsultants.com/
He may be writing the app note but he's not developing and testing circuits that go into the app note unless the manufacturer is populated with maroons like TI. Their app notes read like a lesson from Romper Room.
Reply by February 22, 20142014-02-22
On Saturday, February 22, 2014 1:35:59 AM UTC-5, upsid...@downunder.com wrote:
> On Fri, 21 Feb 2014 16:04:22 -0800 (PST), > > bloggs.fredbloggs.fred@gmail.com wrote: > > > > >On Friday, February 21, 2014 5:56:10 PM UTC-5, Joerg wrote: > > > > > >> > > >> > > >> What some of the Chinese vendors do is copy an example design from a > > >> > > >> datasheet or app note, verbatim. It seems to work. > > > > > >Many times the datasheet or app note is the circuit the device manufacturer developed under contract to an end user. So there's no "seems to work" to it. > > > > However, in many cases a recently hired engineer is set to write these > > application notes to familiarize with company products :-)
Anyone who needs an app note to tell him/her every little thing is lost anyway. App notes advise, they don't teach. If you need to be taught, get some background somewhere else.