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MOSFETs versus BJT in discrete designs

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mawyatt:

--- Quote from: coppercone2 on November 22, 2023, 04:42:11 pm ---what we need is cheaper fabs so we can get what we want instead of relying on piggyback crap

things may not be as grim as you imagine if fab tech gets economized or new construction methods for transistors occur.

--- End quote ---

Why we mentioned the garage bipolar fab based upon leftover old processing equipment.

There is/was a discrete fab that employed leftover higher resolution processing equipment and designed discrete transistors (think MOS and Bipolar) with smaller feature size capability for improved performance, recall Zetex Semi.

Best,

coppercone2:
nah that's not an improvement thought I would not be surprised if someone figured out how to do it twice as cheap and twice as fast if they had the freedom of a garage available with that equipment. i mean some kind of a new machine that someone might make, a different process. there has got to be more creative solutions.

but even any reasonably agile company acquiring this stuff from the old IBMesque places is probobly gonna figure at least 10 awesome things out  :-DD

https://youtube.com/shorts/mGU0pHwNWLk?si=iRjUk-E4eRiOuJJ9

mawyatt:

--- Quote from: David Hess on November 22, 2023, 04:53:44 pm ---
--- Quote from: mawyatt on November 22, 2023, 04:29:09 pm ---Chopper Stabilized and Commutating Auto-Zero techniques allowed pure CMOS to surpass bipolar designs in offset and 1/f noise regions and fully integrable with Digital CMOS.
--- End quote ---

But only for low source impedances and low bandwidths where their high current noise from charge injection is not a problem.  Maybe they now make some parts which solve this, but I have not found them yet.

--- End quote ---

Yeah that's always been an issue, even the CMOS ADCs have this "feature" and why one must pay close attention to the driving source impedance/dynamics of the source driving said ADC. Some Op-Amps were/are specifically designed to drive these Hi Speed ADC inputs without significant induced "ringing" for the dynamic charge injection. Heck even DMMs can do this, we had one long ago (can't remember name tho) that corrupted anything active it measured, a swift hammer correct this potential future problem ;)

Best,

Someone:

--- Quote from: David Hess on November 22, 2023, 04:53:44 pm ---
--- Quote from: mawyatt on November 22, 2023, 04:29:09 pm ---Chopper Stabilized and Commutating Auto-Zero techniques allowed pure CMOS to surpass bipolar designs in offset and 1/f noise regions and fully integrable with Digital CMOS.
--- End quote ---
But only for low source impedances and low bandwidths where their high current noise from charge injection is not a problem.  Maybe they now make some parts which solve this, but I have not found them yet.

--- End quote ---
There are chopper parts coming into the market where the manufacturer is confident in use at "high" impedances. OPAx189 is pretty well proven at this point.

mawyatt:

--- Quote from: coppercone2 on November 22, 2023, 04:42:11 pm ---what we need is cheaper fabs so we can get what we want instead of relying on piggyback crap

things may not be as grim as you imagine if fab tech gets economized or new construction methods for transistors occur.

Some kind of new manufacturing machine. The 3d printer was amazing, maybe there is something that can be made for larger transistors. Years ago I heard the same thing about plastic parts that you will never be able to get high quality complicated plastic parts without a tool and die/mold guy, its only kind of true, even for high quality metal parts.

FAB are vastly overpriced because of the secrecy too. I know that. even adding useless steps to throw off the competition or obsfurate manufacturing technique. and its pretty easy to find someone that says they were ignored about process improvements. All the fab stuff is so tight budget its all based on probability of projections coming through to put ANY money into improving ANYTHING. This is mostly based on hearsay amongst businessmen.... you might consider alot of tech being left behind at a expensive legacy level simply because the bosses think demand might decrease making it unprofitable based on the company history not the cost of the capital (true for any technology outside of the say middle 25% of the bell curve in terms of actual demand and projections). That is, the line runs with the upmost priority being lowest possible severance costs (meaning absolutely bare minimum input towards upkeep and zero input for improvement, for instance something as simple as replacing some manual pressure gauges and valves with a PLC that automates part of some process at costs under 10k dollars when its not even the cost of a months return). this kind of stuff exists! It sometimes even happen because there is no growth expected, even if the demand is not expected to change, if the business strategy chosen happens to be "only put money into things that are likely to grow! we are not even interested in reducing day to day and manufacturing cost because we might grow elsewhere, its what the board wants this quarter!!!!!" this results in something being unbelievably bad but IT EXISTS!!!!!! and if someone wants to do a external industry-info cost study of such a thing, you will get a fucking stone wall bullshitter that makes you think its all running at peak fucking efficiency and its been studied to death, your talkin north korea levels of honesty here

and then there is the geopolitical side of things. that can make it extra stupid. like mega. when you involve washington, and the pentagon, into costs, the ramifications are only the limits of peoples imaginations.

--- End quote ---

Obviously you don't have a semiconductor background, nor bother to study up on things related. Today a new SOTA CMOS fab costs north of $25B, takes over 5 years to come on line and produce the first penny of revenue, and requires continual investments per year well over $1B just to keep up!! TSMC is leading the CMOS charge followed by Samsung, and Intel trying to play catch up!! The USG is trying help the US catch up to what they let out of the bag long ago, thanks to both DC parties involved, and now eventually trying to help US semiconductor technology play catch up.

TSMC with some USG $ assistance, is building 2 SOTA CMOS fabs in US (Az), but coming on-line being delayed because of lack of high level US semiconductor talent, embarrassing indeed!!!

Apple's new M3 chip sets are in TSMC 3nm CMOS process and the most advanced chip has 25 Billion MOS transistors!! If a transistor costs just 1 penny, this chip would cost $250,000,000.00 and yet you can buy a complete Apple computer today for considerable less!! Good example of the massive semiconductor investments paying off in the long run, hopefully someday Apple and Nividia chips will be fabricated on shore!!

We still have a few shinning spots in US advanced technology, semiconductors used to be at the top of that list, but sadly has faded over the years, hopefully the future will bring some of this technology back home.

BTW I do recall something about plastic transistors from way back, and some guy making chips/transistors in his garage, but can't remember details. Funny, that made me think of as a kid about 10~11 getting a couple diodes and connecting them to make a transistor :o

Best

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