Ultra low frequency VCO

Small, hi-Q, but reasonably pull-able, to phase lock.

(Cost never matters to me, I'm never paying ;-) ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | Obama isn't going to raise your taxes...it's Bush' fault: Not re- newing the Bush tax cuts will increase the bottom tier rate by 50%

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Ah, gotcha -- I wans't thinking (the really rather obvious bit) that there's no such thing as a 1575.42MHz crystal. :-)

Speaking of PLLs... do you happen to know why so many of them have rather high (hundreds of MHz) lower frequency limits? E.g., this seemingly-popular part:

... only goes down to 500MHz on one of the PLLs; National has a slightly different version -- -- that goes down to 50MHz. What's different inside, would you think?

Discussions at work here and with Joerg have postulated:

-- AC coupling of the input amplifiers?

-- The fastest counters (dividers) are actually dynamic circuitry, and hence they really can't count too slowly or they forget where they were. (1, 2,

3... umm? 3? 1? Where was I again? La-la-la-la-la I'm so confused!)

There aren't a lot of low-power PLL-based synthesizers in the "more than a handful of MHz"-CD4046 (and derivative) territory and these multi-hundred-MHz+ monsters. We're after some 45MHz PLLs, and so far the ADF4001 is one of the very few attractive-looking candidates.

Thanks for the help,

---Joel

Rather than think "resonator", think very-low-loss shorted-termination transmission line stub. (Think college days :-)

Don't know. Might be AC-coupling internally... makes dividers less prone to offset voltages at those frequencies.

Yep. See above.

Indeed ;-)

I rarely keep track of OTC offerings, since I'm really in the designing whole SOC business.

Occasionally a client will say, "I want all this garbage on a single chip", and hand me a pile of data sheets.

Then I have to analyze how it all works.

That actually works out well with usually significant space and power compaction, since I/O can use up a lot of chip area and power. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Obama isn't going to raise your taxes...it's Bush' fault:  Not re-
newing the Bush tax cuts will increase the bottom tier rate by 50%

Hi Jim,

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Yeah, that's becoming a bit unfortunate for those of us doing board-level designs where the quantities just aren't there for doing custom ICs -- many of the RF parts that are left aren't particularly optimized for power consumption, since they're either parts that have been around forever (big transistors, I suppose) or they're aimed at the aerospace/military market where they figure you've got a nuclear reactor to power the thing.

We're got a wireless handheld (battery-powered) widget that, between the numerous synthesized LOs, mixers, and amps might double as a pretty good hand-warmer. :-)

---Joel

Post your questions and I'll try to answer.

Larkin will certainly jump in and shovel a pile of BS in your direction :-)

I'm thinking the way to resolve this Larkin statement, "... charge is not conserved" in...

Message-ID:

is for me to post the solution on my website.

BUT in a password-protected ZIP file.

White-listed individuals can contact me for the password and see how it works, that way Larkin will be prevented from seeing it and claiming "that's what I really meant... let him choke on his own drool :-)

I'll let you know when it's up there.

Funny. Yesterday, while cooling my heels at a going-away swim party for a granddaughter (they're moving to Rancho Mirage... Renee's father is in ill-health, so she's going to run his automotive parts business), I sat there in the shade, in 112°F heat and "played" the circuit in my head... that's how I figured out where the missing charge comes from ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Obama isn't going to raise your taxes...it's Bush' fault:  Not re-
newing the Bush tax cuts will increase the bottom tier rate by 50%

a time

are the same in

really

application and

your

the

make

reliable

Now what is the equivalent bandwidth of -100 dBc for a 60 Hz carrier? Since you said 20 log() basis 60 * 10^-5 is 600 microHz. That would have to take some minutes, and if you wanted a proper 10 to 1 measurement buffer, it takes ten times longer. Call it 10,000 seconds? A few hours. And the reference stability etc., i remarked on is coming into play.

could do

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I am sorry. I think i am misreading your post, are you saying you can get a 1 MHz deviation on a 60 Hz carrier? Naw, you must be trying to say something else and i misunderstood.

You're confused, I'm afraid. -100 dBc phase noise in a given bandwidth (say 1 Hz, but it doesn't matter) is 7 microradians RMS. Using a 5V swing and a CMOS analogue gate as a phase detector, that's

dV = 7e-6 rad RMS * 5V/(pi rad) = 11 microvolts RMS,

which is trivial to measure in a 1 Hz bandwidth in a few seconds--it's

80 dB above the noise of a good op amp, so you just have to wait for the filter to settle.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

You can put a 1 MHz phase modulation on a 60 Hz carrier, but you sure don't wind up with anything pretty. For instance, you could put the 60 Hz on a varactor-loaded transmission line, and drive the varactors with

1.000000000 MHz. As long as the varactors were driven really differentially, you wouldn't get any 1.000000000 MHz on the line.

That's way outside the quasistatic limit, of course, which is where we're all used to working. It would be a nasty splattery mess, but you'd get _something_.

But that wasn't the point I was trying to make. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

Sorry to be slow responding. That's an interesting point about the noise gain of the oscillator. I think we agree that the OPA378 is okay down to 1 Hz offset or thereabouts, anyway. (It's a very nice part btw--I'm using it in some millihertz things just now.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

That is really good since GPS itself is not that old.

I did my first Garmin chip more than 20 years ago. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Obama isn't going to raise your taxes...it's Bush' fault:  Not re-
newing the Bush tax cuts will increase the bottom tier rate by 50%

To put this into perspective, national and continent wide mains networks are typically operated so that the 24 h average cycle count exactly match the nominal mains frequency, so that synchronous clocks would remain correct on average for long periods of time (days, months).

However, the instantaneous frequency error can be several thousand ppms and while the time error is usually kept below +/-30 s so that clocks with hour and minute displays only would not be in error more than for the last digit, this corresponds to up to +/-650.000 degrees total phase error during the day.

Actually I realized what's been bothering me about this whole thread as I wrote the above today. Just specifying 100dBc is practically meaningless -- any oscillator is going to have some phase noise, and it's going to grow the closer you get to the carrier. White noise in the amplifying element will turn into noise that goes as 1/(f-f0), and no matter what you do you'll have 1/f noise in the amplifying element that'll start cutting in at _some_ point. So you can always make any

60Hz oscillator meet a 100dBc requirement -- just find a bandwidth for the measurement that makes it work. Ditto, you can take any oscillator and narrow up the bandwidth around the carrier to make it fail just about any dBc phase noise requirement. Even a super-zoot cesium fountain oscillator is going to have "phase noise" that exceeds 100dBc if you wait around long enough.

So I guess that all of the suggestions that have been given will work. Or none of them. Or some, if only the OP would tell us the rest of his requirement.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

The OP seems to be interested in syncing his PV solar system to the grid, at least thats what I infer from reading some other of his posts. Kind of makes the 100dBc spec look silly if so.

No kidding! If he's within 10 degrees one way or another that's probably plenty good.

Of far greater concern with PV usage is making sure that putting what is essentially a negative resistance on the line won't cause instability, or at least knowing exactly what conditions will lead to instability so that you may avoid them during installation.

Particularly if you're going to move from your lab with one or two PV panels attached to a good solid grid, to some solar farm out in the boonies where your PV array is the biggest power source for miles.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

Genuine phase noise sidebands have flat tops, so they aren't as sensitive to modulation frequency as FM noise. Various authors go to various lengths in trying to identify regions where the noise goes as

1/f, 1/f**2,.... I expect that the OP just wanted a 60 Hz oscillator that was quiet enough that he didn't have to worry about it, due to being hip deep in alligators of another species.

(I actually have a confirmed seat on the one flight from ATL to JFK that looks like making it this afternoon--all the LGA and EWR (La Guardia and Newark) folk are upschkrauen. Gotta run.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

What in the world are you saying? Sounds kind of ignorant to me =85 but I=92ll reserve judgment until you answer.

I made a living at designing multiloop uw / rf synthesizers and taking this statement as fact sure wouldn=92t have helped.

regards

Is anyone here younger than 20? 40? I know a few aren't yet 60. ;-)