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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: Yttrium iron garnet
Date: Fri, 31 May 2024 21:24:33 +1000
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On 31/05/2024 8:40 pm, john larkin wrote:
> On Fri, 31 May 2024 00:04:47 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
> 
>> john larkin <jl@650pot.com> wrote:
>>> On Thu, 30 May 2024 21:46:20 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>> john larkin <jl@650pot.com> wrote:
>>>>> On Thu, 30 May 2024 11:03:19 GMT, Glen Walpert <nospam@null.void> wrote:
>>>>>> On Thu, 30 May 2024 09:14:58 -0000 (UTC), Cursitor Doom wrote:
>>>>>>> On Thu, 30 May 2024 15:45:21 +1000, Bill Sloman wrote:
>>>>>>>> On 30/05/2024 3:37 am, john larkin wrote:
>>>>>>>>> On Wed, 29 May 2024 17:12:21 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:
>>>>>>>>>> On Wed, 29 May 2024 13:52:34 +1000, Bill Sloman wrote:
>>>>>>>>>>
>>>>>>>>>>> Yttrium iron garnet tuned oscillators were around back then, but
>>>>>>>>>>> their 2GHz to 8GHz range was too high for me to count with the
>>>>>>>>>>> integrated circuits around then - we had to go the Gigabit Logic's
>>>>>>>>>>> GaAs parts to get to 800MHz, and that became the unique selling
>>>>>>>>>>> point of the system.
>>>>>>>>>>
>>>>>>>>>> YIG oscillators were quite the thing back in the day, but I'm
>>>>>>>>>> guessing they've been completely superseded by now to get to ever
>>>>>>>>>> higher frequencies. Seems we've gone from -
>>>>>>>>
>>>>>>>> This misses Jan Panteltje's thread "Small magnetic tunable filter for
>>>>>>>> 6G and beyond" which is about Yig being used today.
>>>>>>>
>>>>>>> That article makes it seem like YIG is some revolutionary, new, emerging
>>>>>>> technology!
>>>>>>
>>>>>> Use of YIG filters as a replacement for varactor tuning could turn out to
>>>>>> be significant.  2022 Microwave Journal article:
>>>>>>
>>>>>> <https://www.microwavejournal.com/articles/37980-reinventing-yig-
>>>>>> technology-for-microwave-filter-applications>
>>>>>
>>>>> The VIDA oscillators still look like giant expensive power hogs. They
>>>>> don't specify modulation bandwidth on the data sheets that I see, but
>>>>> it must be terrible.
>>>>>
>>>>> One can't modulate a hundreds-of-mA electromagnet very fast.
>>>>>
>>>>> An LC osc with a varicap is a more sensible VCO. Narrowband, one can
>>>>> varicap a coaxial ceramic resonator, or a PCB ring oscillator, or
>>>>> something. Cheap and fast.
>>>>
>>>> And far, far noisier than the best YIGs.
>>>
>>> Coaxial ceramic resonators have Qs in the thousands, and low tempcos.
>>>
>> If you can find one at the exact frequency you need.  YIGs have a huge
>> tuning range.
>>
>> IIRC you also said that they’re piezoelectric.
> 
> The CCRs are high-K, usually shorted, transmission lines, not
> piezoelectric. Prop delay is a tiny fraction of c. You can TDR them as
> such. Z is usually in the 10 ohm ballpark.
> 
>> I’m not saying that YIG is the answer to everything, but for some things
>> it’s amazing and (AFAIK) unique.
> 
> No argument, but they will always be big and expensive slow-tuning
> power hogs, which is fine in a spectrum analyzer.

Except that they don't have to be, as

https://www.nature.com/articles/s41467-024-47822-3

pointed out. Modern lithography and surface mount assembly can let you 
get away with a much smaller active device, and if you get the bulk of 
your magnetic field from a permanent magnet, you don't need a lot of power.

> RF synthesizer chips are pretty amazing these days too. They make a
> pretty good first LO too, but they are small and cheap.

Not all that cheap, and there's quite a bit higher harmonic content to 
filter out.

>> Sure improves spectrum analyzers!
> 
> I wonder if the latest SAs use YIGs.

Keysight's do.

https://docs.keysight.com/kkbopen/yig-spheres-the-gems-in-your-signal-analyzer-604584429.html

-- 
Bill Sloman, Sydney