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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: BAW
Date: Sat, 25 Jan 2025 09:05:42 -0800
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On Sat, 25 Jan 2025 13:55:05 +0000, Cursitor Doom <cd@notformail.com>
wrote:

>On Fri, 24 Jan 2025 17:46:24 -0800, john larkin <JL@gct.com> wrote:
>
>>On Sat, 25 Jan 2025 00:41:39 +0000, Cursitor Doom <cd@notformail.com>
>>wrote:
>>
>>>On Wed, 22 Jan 2025 17:09:29 -0800, john larkin <jl@glen--canyon.com>
>>>wrote:
>>>
>>>>On Thu, 23 Jan 2025 00:55:25 +0000, Cursitor Doom <cd@notformail.com>
>>>>wrote:
>>>>
>>>>>On Wed, 22 Jan 2025 10:55:39 -0800, john larkin <jl@glen--canyon.com>
>>>>>wrote:
>>>>>
>>>>>>On Wed, 22 Jan 2025 18:07:06 +0000, Cursitor Doom <cd@notformail.com>
>>>>>>wrote:
>>>>>>
>>>>>>>On Mon, 20 Jan 2025 16:26:10 -0800, john larkin <JL@gct.com> wrote:
>>>>>>>
>>>>>>>>On Mon, 20 Jan 2025 19:52:03 -0000 (UTC), Phil Hobbs
>>>>>>>><pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>>>>>
>>>>>>>>>john larkin <jl@glen--canyon.com> wrote:
>>>>>>>>>> https://www.ti.com/product/CDC6C
>>>>>>>>>> 
>>>>>>>>>> These are like 35 cents at 1K.
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>
>>>>>>>>>Of course a crystal oscillator is a BAW device too. ;)
>>>>>>>>>
>>>>>>>>>Cheers 
>>>>>>>>>
>>>>>>>>>Phil Hobbs 
>>>>>>>>
>>>>>>>>Don't get technical with me!
>>>>>>>>
>>>>>>>>I wonder if it's all silicon, a sort of bulk MEMS thing. The price is
>>>>>>>>absurd. I guess every one has to be trimmed to frequency.
>>>>>>>
>>>>>>>Phil's pretty good in that regard. There are some people who see
>>>>>>>everything in terms of equations and use higher mathematics to explain
>>>>>>>their function. A xtal oscillator would provide a very simple example
>>>>>>>for such persons to exhibit this (most unfortunate) character trait.
>>>>>>
>>>>>>Phil is one of those people who can see equations in motion. I can't.
>>>>>>I operate on instinct and simulation.
>>>>>>
>>>>>>We have brainstormed on some pretty important projects and generated
>>>>>>some ideas that influence most everyone here. The skills are
>>>>>>complementary.
>>>>>>
>>>>>>His book is good to have if you design electro-optics or low-level
>>>>>>analog stuff.
>>>>>>
>>>>>>https://www.amazon.com/Building-Electro-Optical-Systems-Making-Applied/dp/1119438977/ref=sr_1_fkmr0_1?crid=3M9PG1T68443R&dib=eyJ2IjoiMSJ9.xIlGO_AWviZZRYMlHFKJuNzKnLc8MDBpUjgE7RsYsDk.WiFCuc8GjBlGtPimMCFx0kOu5NieBv0TzXDNCokyLQM&dib_tag=se&keywords=phil+hobbs+optics&qid=1737571796&s=books&sprefix=phil+hobbs+optics%2Cstripbooks%2C138&sr=1-1-fkmr0
>>>>>>
>>>>>>Be cautioned that there are equations.
>>>>>
>>>>>Equations are fine (unavoidable anyway) in this science. But it's not
>>>>>helpful in the first instance to gain an intuitive idea of how
>>>>>something works - unless you're one of the people I mentioned above.
>>>>>This is my main issue with Tom Lee's otherwise superb book, 'Planar
>>>>>Microwave Engineering' where he typically launches into higher
>>>>>mathematics almost from the get-go.
>>>>
>>>>I have that book. It's mostly useless. One equation will be a full
>>>>page of fine print, and then the next page turns out to be one term of
>>>>that equation.
>>>
>>>
>>>Indeed. Not only that, but the mathematics is unfamiliar. I know most
>>>of the equations for transmission line theory by sight, but the ones
>>>Tom cites are completely different and tend to use a lot of Greek
>>>letters which relate to physical constants I've never even heard of.
>>>On the other hand, where he doesn't use unfamiliar mathematics,
>>>there's a *lot* in there I haven't seen any any other RF books which I
>>>find really interesting.
>>
>>It's easier to design with a geometry for which there are good
>>calculator programs.
>>
>>We have used ATLC to do e/m simulations of transmission line cases.
>>
>>https://www.dropbox.com/scl/fi/6kdejmbybk4u5mq1xjait/Edge_alone_4.jpg?rlkey=volom4afazo44o6cpedgl89ge&raw=1
>>
>>https://www.dropbox.com/scl/fi/82ysq5m13br8ahubdi4z7/Rob1.jpg?rlkey=4bnm3uu5otfolka9gqsov5tel&raw=1
>>
>>https://www.dropbox.com/scl/fi/ogfqs1m93mf1uw80hwkpi/Rob_51_ohms.jpg?rlkey=u4q3fumbzwmpojck5ih88c45q&raw=1
>>
>>That one butchers a multilayer PCB stack to get a good match with a
>>cheap edge-launch SMA connector.
>>
>>https://www.dropbox.com/scl/fi/n7hlatrxdoiywfkvebqj9/DSC01527.JPG?rlkey=hycib2nrk4zv662mu5vndy23g&raw=1
>>
>
>I had to google ATLC simulator as I've not heard of it before. Anyway,
>these plots are all very interesting, but you have no way of verifying
>their accuracy AFAICS.
>You mentioned a while ago you had a good source for cheap but
>reasonable quality edge connectors (Aliexpress?) Can you post a link
>to them please?

ATLC2 is a bit easier to drive.

The way to verify a sim is to make a board and TDR it. They are
usually close.

The one in the pic above is from Shining Star.

SHINING STAR        19521000

We use 

SHINING STAR        24521116

too, a bit longer part. Both about $1.90.


I've bought a bunch of similar ones from Amazon and they have been
great. But it's our general policy to not use Amazon parts in
production.

Here's a 4-layer proto board that let us TDR the connectors and the
relay.

https://www.dropbox.com/scl/fi/bvcnqnvb4euc7pqw7wzab/DSC06884.JPG?rlkey=q1op81z1bumkfxoq8d5mtzi91&raw=1