Ping Jim Thompson Sine Shaper question ????

A simple comon-collector Colpitts with two variacs back-to-back. I did this in the 1980's. Octave bandwidth no problem. Horrible phase noise.

The problem with LC oscillators at UHF is phase noise. They are ok for TV, but not for engineering work. Look at Leeson's equations with the updates from Ulrich Rohde.

One approach is octave-bandwidth YIG oscillators. Then the problem is counting down the microwave frequency to usable sub-gigahertz frequencies.

Binary counters are noisy. Regenerative dividers are better, but are claimed to have a very narrow bandwidth. See Wenzell for examples. I have developed an approach to octave-bandwidth regenerative dividers that work well into the x-band and above.

The next challenge is Whispering Gallery resonators. These require cryogenic superconductive cavities and are not very commercial. However, Ulirch has posted the ability to match Whispering Gallery at room temperature. I really wish he would post more info.

Another approach is optical fiber. 25 km of low-loss fiber has an extremely sharp phase curve. One problem is phase noise, then locking on the desired frequency.

The next stop is optical combs. Apparently some optical atomic resonances are around 25Hz wide at THz frequencies. When this is downconverted to microwave frequencies, you get ADEV's around 1e-18. That means if you raise the oscillator by 1 cm, it will go out of calibration.

About the best practical references is GPS-disciplined Rubididum clocks with a low phase noise OXCO clock to filter the Rubidium noise. SRS has offered a long-life Rubidium with a built-in low phse noise oscillator to reduce the phase noise. These guys are pretty good.

Broadcom has announced a new GNSS chip intended for smartphones that offers cm-accuracy in cities concrete canyons. It uses the L1 and L5 frequencies to correct for ionospheric delay. This is interesting, but it is not clear if the chip has 1 pps output required for time stabilization. Probably not. That is not their interest.

So the hunt goes on.

You went round the whole bus route and came back again, I gather.

Still looking to learn from the details of your low noise oscillators, whenever you feel like sharing.

Cheers

Phil Hobbs

You don't want me. I'm a two-bit player. Most of my stuff doesn't work.

There are hundreds of top-notch players far better than me. See Ulrich Rohde, John Miles, Enrico Rubiola, FL Walls, Bruce Griffiths, Leif Asbrink SM5BSZ, and many others. Their work is world class.

I'm still playing catchup.

I'm not the one-trick-pony, Shorty.

I almost forgot one of the most important.

A General Theory of Phase Noise in Electrical Oscillators Ali Hajimiri, Student Member, IEEE, and Thomas H. Lee, Member, IEEE

URLs keep changing. Search google.

More the no-trick donkey.

--
Bill Sloman, Sydney

I use the "microwave brick" phase locked oscillators for my X-band ham radi o microwave hobby. The sapphire or glass "tuned dielectric rod in cavity" oscillator works very well for low phase noise. However as telecom marche s on, fewer and fewer of them are made, and I rue the coming day when I can not find them used, any more...

On a emotive note

That said, Tauno, thanks for the beautiful spice model. You made my day. I spent an hour playing with that. If I the design at different points and sum, I could get some extra useful waveforms out of that.

The university downsized, and I am the last electronics generalist left on the tech staff. So I'm so overloaded at work that stress is coloring my th ought. I can't walk down the hallway without a grad student yelling "Hey St eve".

Steve

Thanks.

Please note that the amplitude to be handled is restricted by the zener voltage of the base-emitter junctions (about 6 to 8 V).

--

-Tauno

International Trade sometimmes has its bummers:

(CNN) When they discovered what was going on, US authorities were shocked. A man named Xiang Li was selling high-end defense software from his home in Chengdu, China ...

--

Hi Steve, Apologies for my slow response... just up to my ears in finishing a chip circuit design in, even for me, a record 9 weeks ;-)

And I solved a few problems... I can now make an LDO that doesn't need ESR in the load cap to be stable; and I cooked up a bandgap that runs on 0.5uA!

Back to your shaper requirement... what will be the source of the triangle wave? The 8038 has a _bizarre_ triangle wave buffer. Might you be using a 555 timer for the triangle wave? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website. 

Thinking outside the box...producing elegant & economic solutions.

you could use a PTC thermistor, but it's more succeptable to ambient temperature modulating amplitude.

yeah, for under a buck a DDS isn't going to work well above a few kilohertz

--
This email has not been checked by half-arsed antivirus software

Wow. How good (or bad) was the noise and the tempco?

Allan

Noise, I have no idea, nor care... strictly for a down regulator for

1.8V logic from a 3.3V source. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 |

I'm looking for work... see my website.

Thinking outside the box...producing elegant & economic solutions.

Avoid transistor matching and TC issues, use 3x Quad OpAmps plus

8-diodes...

This was based on an LM555 as the triangle-wave source (and tracks it)... bias ends of resistor string accordingly for other sources. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website. 

Thinking outside the box...producing elegant & economic solutions.

Ran extended Fourier out thru 9th harmonic: 0.71% distortion. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website. 

Thinking outside the box...producing elegant & economic solutions.

Thanks Jim, That's perfect. I need to order some resistors and build it!

Steve

Enjoy! ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 |

I'm looking for work... see my website.

Thinking outside the box...producing elegant & economic solutions.

Another pointer. Choose quad OpAmps for rail-to-rail output. That will ensure that shared bias circuits won't interact when one OpAmp in the chain rails. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 |

I'm looking for work... see my website.

Thinking outside the box...producing elegant & economic solutions.

did you mean singles?

NT