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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: Yttrium iron garnet
Date: Fri, 31 May 2024 13:29:02 +0200
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On 5/31/24 12:40, 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 guessing they've been completely superseded by now to get to ever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.
> 
> RF synthesizer chips are pretty amazing these days too. They make a
> pretty good first LO too, but they are small and cheap.
> 
>>
>> Sure improves spectrum analyzers!
> 
> I wonder if the latest SAs use YIGs.
> 
> 
>>
>> Cheers
>>
>> Phil Hobbs

I gather many spectrum analyzers these days mix successive
slices of the spectrum down to where an ADC can acquire the
whole slice, and the remaining processing is all software FTs.

No need for YIG oscillators, and the LO synthesizer needs
only coarse steps.

Jeroen Belleman