The point is that a lot of this jiber-jaber is pointless. Without the OP giving a better definition of the problem it=92s a guess at best which measurement technique is required.
He never did state the basis for his phase noise number, nor did he have an offset frequency.
The challenge in making =96100 dBc or better measurements is a function of the offset frequency and bandwidth. Center frequency isn=92t the issue here.
You may not be interested, but perhaps other folks are. And how big an offset frequency can he have on a 60 Hz carrier, anyway?
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
There's no one-up-man-ship involved. Larkin won't (or can't, because he doesn't really understand it) show where the extra charge came from. You (or Win) could put a stop to Larkin's nonsense. Larkin displays me as a fool, and the newbies don't know any better, so they'll never ever learn the correct solution unless someone (politically :) respected steps in.
Yep. ...Jim Thompson
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| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
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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%
It=92s not that it=92s not interesting =85 but you need to change the topic to phase noise measurements or something of that nature. Or stable low freq Osc for example.
It appears that the OP wanted to discipline to line and use that as a long term ref.. It=92s not clear to me how he came up with the =96100 dBc number without an offset =85
I=92m not sure what you mean by =93how big an offset=94 =85 offset generall= y refers to the position of the measurement relative to the carrier. The closer the offset the more difficult the measurement ... generally do to the limitation of the measuring equipment. The interesting part is the solution to those challenges.
I=92m not trying to be a malcontent here =85 just seems like the discussion doesn=92t have direction.
Much faster than Q cycles, I mean. (Posted before breakfast in Albuquerque.)
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
Understood. I agree that the OP's question wasn't that well posed, but there was a bunch of very strongly stated Bad Info here that needed pointing out. I took the OP to be saying "I need a 60 Hz oscillator block that's way, way quieter than I know how to build", and that the rest of us have been making suggestions. Calculating or measuring how good it actually is is his worry.
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
One interesting and often overlooked part is the coaxial ceramic resonator. It's essentially a shorted transmission line formed in a block or tube of hi-K ceramic, usually by silver or copper plating it. They are usually treated by the RF boys as resonators or inductors, but they really act like time-domain transmission lines. TCs are in the single-digit PPMs and Qs in the hundreds or thousands. Dielectric constants are in the hundreds or thousands, so they are very short for their delay/frequency.
Remarkable parts. I use them to make instant-start/instant-stop oscillators in the 600 MHz range. As a VCO, they will have very low phase noise, somewhere between an LC and a quartz crystal.
John
Check out La Posada de Albuquerque. Cool old hotel. Or it was, except they may have "upgraded" it.
John
I don't know about that. It isn't that difficult to calculate a circuit with two caps, an inductor, and an elf who opens and closes a switch at the right moments. It does help to know elementary differential equations.
I haven't actually followed the original discussion closely enough to know who made the first technical error. The larger error IMO is to keep getting into these tiresome p***ing contests, which I decline to do. If what you want is merely to have the correct solution posted, post it and let's move on to some electronics.
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
I confess I'm one of the ones who overlooked them...where do you get them, and do they come in Y5V?
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
I don't think any specific problem has been clearly stated, such that it can be analyzed. My comment, that seems to have ruffled feathers, is that one shouldn't assume as a working tool that charge, coulombs stored in various capacitors in a circuit, is conserved. Sometimes it is, sometimes it isn't, sometimes the concept is silly.
The argument did make me go back and review some basics, which is good. Messing with all this digital and software and opamp stuff can make the old EE101 math get rusty.
John
Don't know. We buy ours from Skyworks/Trans-tech, and they have Er values from 10 to 90. TCs are very good somehow. Lots of people make these things and the little, high-frequency ones are cheap in quantity.
John
e
Yes! I've enjoyed the discussion. Say could someone explain the the
100 dBc of phase noise spec. I've been thinking of this a one part in 10^5 of jitter in the period. So for instance a 1 Hz signal the jitter is less than 10 micro seconds aand for a 1 MHz signal a jitter of 10 pico seconds.Is that right?
George H.
The usual oscillator phase noise spec would be " -100 dBc/Hz " at some offset frequency from the carrier. It's often given as a curve. It is possible to convert the curve to an RMS jitter spec... I have a program around somewhere that some s.e.d. guy posted.
John
Dodge, dodge, dodge. You specifically stated, in...
Message-ID:
"... charge is not conserved."
Where, oh great pretend guru, where does the excess charge come 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%
This actually kind of makes my point, which I didn't state clearly: if you _don't_ use a divider it'll be hard. With a divider it gets easy, as long as you ignore clock jitter in the divider (and clock jitter probably isn't a big deal, given the output frequency).
Depending on how close to the carrier you want to get, you lose a factor of up to infinity (if you get _really_ close to the carrier).
The noise gain is something like 1/(s^2 + w0^2) -- it's an oscillator. Worse, because it's an RC, the constant you're multiplying by is greater than one -- I get Hn(s) ~ 15/(s^2 + w0^2). That's not taking the current noise of the part into account (which, I admit, I haven't checked on because I'm lazy).
1Hz away your noise gain is just about 200, for 4uV/sqrt(Hz). That's doing OK, but at 0.1Hz away the noise gain is about 2000 -- all you have to do is measure close enough to the carrier at a wide enough bandwidth and your noise is too high (sure would be nice if the OP specified what he wanted, but I think we lost him).-- 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
I've been "using" them... designing them into GPS LO's since before you were born ;-) ...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%
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
[coaxial ceramic resonators]
What's the advantage -- for you -- over crystals? Just lower cost?
---Joel
Small phase jitter is the quadrature partner of small amplitude noise.
Say you have a pure carrier and add ordinary white noise, e.g. by putting a resistor in series with the perfect oscillator's output. The resulting RMS phase deviation in some given bandwidth is
= 1/(sqrt(2*CNR))
where CNR is the carrier to noise ratio (i.e. carrier power/noise power in the given bandwidth). The factor of sqrt(2) expresses the fact that the noise and signal are uncorrelated, so that half the noise power winds up in the I phase as amplitude noise, and half winds up in the Q phase as phase noise.
You can derive this from the formula for sums and differences of sines and cosines plus an orthogonality argument--it's quite pretty. It's in my section 13.6 (either edition), but that derivation almost certainly isn't original with me. One very pleasant consequence is that the phase noise statistics are the same as those of the additive noise in the high-CNR limit where the formula applies.
The universality of this formula is why essentially all FM and PM detectors have equivalent performance at high SNR--where the additive model breaks down is low SNR, where FM/PM detection schemes really differ in performance.
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
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
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