Teardown of a quartz crystal oscillator and the tiny IC inside
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Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#2> I was expecting a gem-like quartz crystal inside, but found that oscillators use a very thin disk of quartz.
Interesting - watches usually use a tuning fork shape. I wonder why they use a disc here?
> Wristwatches were revolutionized in the 1970s by the use of highly-accurate quartz oscillators.
If you're into highly accurate timepieces you can pick up some amazing quartz pieces from brands like Rolex (the OysterQuartz) and Audemars Piguet (the AP Royal Oak 6005) from this time. Since brands wanted to distinguish their quartz movements from their mechanical ones the cases the quartz pieces come in are very distinct.
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#3> I was expecting a gem-like quartz crystal inside, but found that oscillators use a very thin disk of quartz. Interesting - watches usually use a tuning fork shape. I wonder why they use a disc here? > Wristwatches were revolutionized in the 1970s by the use of highly-accurate quartz oscillators. If you're into highly accurate timepieces you can pick up some amazing quartz pieces from brands like Rolex (the OysterQu…
> I wonder why they use a disc here?
It has been a long time since I've thought about it, so I might be misremembering, but the crystal geometry can influence skew related to orientation and external vibration. A crystal + IC design is using the crystal as more of a bandpass filter than an actual signal source, so it would make no sense to introduce the downsides of a tuning fork for a design that makes no use of the actual tuning fork quality.
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#4> I was expecting a gem-like quartz crystal inside, but found that oscillators use a very thin disk of quartz. Interesting - watches usually use a tuning fork shape. I wonder why they use a disc here? > Wristwatches were revolutionized in the 1970s by the use of highly-accurate quartz oscillators. If you're into highly accurate timepieces you can pick up some amazing quartz pieces from brands like Rolex (the OysterQu…
It's a function of size. Tuning fork crystals generally have frequencies in the range of a few tens of kilohertz (generally 32768 Hz).
Quartz discs vibrate at many megahertz. A tuning-fork like structure that oscillated at 100 MHz would be far to small to easily manufacture.
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One fun note: crystals like this are used for measuring deposited material in vacuum processes like PVD [1] or similar [2]. The crystal is exposed inside the vacuum chamber where it will be deposited on at the same rate as the target, and the change in frequency is a direct function of the mass (and therefore thickness) of the deposited material.
Eventually, the exposed crystal has to be replaced as it no longer oscillates properly.
1: https://en.wikipedia.org/wiki/Physical_vapor_deposition 2: https://www.semicore.com/news/72-thin-film-deposition-contro...
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#5For early microprocessors, the application manual would often devote 20 pages to selection and support of a crystal oscillator. For wide-temperature range use, as in industrial circuits, it could be a good rule-of-thumb to budget for a self-contained powered oscillator in the BOM.
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#6> I was expecting a gem-like quartz crystal inside, but found that oscillators use a very thin disk of quartz. Interesting - watches usually use a tuning fork shape. I wonder why they use a disc here? > Wristwatches were revolutionized in the 1970s by the use of highly-accurate quartz oscillators. If you're into highly accurate timepieces you can pick up some amazing quartz pieces from brands like Rolex (the OysterQu…
It's a function of size. Tuning fork crystals generally have frequencies in the range of a few tens of kilohertz (generally 32768 Hz). Quartz discs vibrate at many megahertz. A tuning-fork like structure that oscillated at 100 MHz would be far to small to easily manufacture. ------ One fun note: crystals like this are used for measuring deposited material in vacuum processes like PVD [1] or similar [2]. The crystal i…
Note 32768 Hz is chosen because it is a power of 2 (the 15th power).
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#7For early microprocessors, the application manual would often devote 20 pages to selection and support of a crystal oscillator. For wide-temperature range use, as in industrial circuits, it could be a good rule-of-thumb to budget for a self-contained powered oscillator in the BOM.
And lots of them had built-in oscillators only requiring a crystal, or even a resonator for low cost applications where timing wasn't all that critical.
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#8Btw, am I the only one that would love to see FW-91W?
Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#9> I was expecting a gem-like quartz crystal inside, but found that oscillators use a very thin disk of quartz. Interesting - watches usually use a tuning fork shape. I wonder why they use a disc here? > Wristwatches were revolutionized in the 1970s by the use of highly-accurate quartz oscillators. If you're into highly accurate timepieces you can pick up some amazing quartz pieces from brands like Rolex (the OysterQu…
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Re: Teardown of a quartz crystal oscillator and the tiny IC inside
#10Almost 40 years old technology and we are still unable to "print" these dies at home.
Can you imagine how much fun that would bring if you could design your own IC and just hit print, then load the die into the carrier and solder the pins?
There isn't even a service like JLCPCB where you could get your custom ICs made and shipped to you.