General > General Technical Chat
Analog Devices in talks to buy Maxim
SilverSolder:
--- Quote from: David Hess on July 14, 2020, 12:55:00 pm ---I still remember when Analog Devices bought PMI (Precision Monolithics Incorporated).
Fabrication processes are also dependent on suppliers and this is a major problem for old linear processes.
--- End quote ---
I'm really surprised that older designs can't be "emulated" on newer processes. - Perhaps they can... but not without quite a bit of engineering effort that perhaps approaches a redesign - maybe like an ASIC or something?
coppice:
--- Quote from: SilverSolder on July 14, 2020, 01:17:49 pm ---
--- Quote from: David Hess on July 14, 2020, 12:55:00 pm ---I still remember when Analog Devices bought PMI (Precision Monolithics Incorporated).
Fabrication processes are also dependent on suppliers and this is a major problem for old linear processes.
--- End quote ---
I'm really surprised that older designs can't be "emulated" on newer processes. - Perhaps they can... but not without quite a bit of engineering effort that perhaps approaches a redesign - maybe like an ASIC or something?
--- End quote ---
I'm puzzled why you would expect to be able to emulate older processes in newer fabs. They don't just keep shrinking the geometries. The chemicals used, the etching techniques, everything changes over time. You probably couldn't even find the database needed to generate a new mask set that would fit in the modern equipment.
David Hess:
--- Quote from: SilverSolder on July 14, 2020, 01:17:49 pm ---
--- Quote from: David Hess on July 14, 2020, 12:55:00 pm ---I still remember when Analog Devices bought PMI (Precision Monolithics Incorporated).
Fabrication processes are also dependent on suppliers and this is a major problem for old linear processes.
--- End quote ---
I'm really surprised that older designs can't be "emulated" on newer processes. - Perhaps they can... but not without quite a bit of engineering effort that perhaps approaches a redesign - maybe like an ASIC or something?
--- End quote ---
Those designs are tailored to the specifics of the fabrication process.
So for instance the old NPN only processes included slow and low gain lateral PNPs made with NPN process steps but those PNPs cannot be replaced with the PNPs on a more modern complementary bipolar process if the old design relied on the 30+ volt base-emitter breakdown voltage of those old PNPs, like almost every operational amplifier with a wide differential input voltage range, including the LM324, 741, and 301A. The "modern" replacements for those parts which are built on a "superior" complementary bipolar process are limited to about 7 volts.
If you look through the Linear Technology parts portfolio, there are cases where an older part was redesigned but they used a modified part number for the new part, so it does happen but usually the old part remains available.
SilverSolder:
--- Quote from: coppice on July 14, 2020, 01:33:49 pm ---[...]
I'm puzzled why you would expect to be able to emulate older processes in newer fabs.
They don't just keep shrinking the geometries. The chemicals used, the etching techniques, everything changes over time. You probably couldn't even find the database needed to generate a new mask set that would fit in the modern equipment.
--- End quote ---
Too much exposure to software, I guess! :D
To a software engineer, using a virtual machine to emulate an older architecture is a commonly used approach, and gives "near perfect" albeit not 100% exactly the same result as the original designs - but "good enough for Australia", even though the new technology it runs on has absolutely nothing to do with what was available back when the original was designed.
It doesn't seem beyond imagination that an older part could be emulated with a newer design, one that might have a completely different schematic diagram that suits the newer processes, yet ends up behaving like the older part at least on a "good enough for Australia" basis?
coppice:
--- Quote from: SilverSolder on July 14, 2020, 03:53:28 pm ---
--- Quote from: coppice on July 14, 2020, 01:33:49 pm ---[...]
I'm puzzled why you would expect to be able to emulate older processes in newer fabs.
They don't just keep shrinking the geometries. The chemicals used, the etching techniques, everything changes over time. You probably couldn't even find the database needed to generate a new mask set that would fit in the modern equipment.
--- End quote ---
Too much exposure to software, I guess! :D
To a software engineer, using a virtual machine to emulate an older architecture is a commonly used approach, and gives "near perfect" albeit not 100% exactly the same result as the original designs - but "good enough for Australia", even though the new technology it runs on has absolutely nothing to do with what was available back when the original was designed.
It doesn't seem beyond imagination that an older part could be emulated with a newer design, one that might have a completely different schematic diagram that suits the newer processes, yet ends up behaving like the older part at least on a "good enough for Australia" basis?
--- End quote ---
If you want a new part which broadly emulates an old part, that kind of thing is being developed all the time. The original topic was sustaining production of a guaranteed compatible drop in part. A new part will generally require a whole new design around it. For example, a modern part will generally require a lower supply voltage, and have different voltage ranges on its I/O pins, etc. A broad range of more subtle differences, like tolerance to EMI, will also need to be allowed for in a new design using the new part.
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