I saw a talk by one of the authors, Rahul Sarpeshkar, who had just finished a postdoc at Bell Labs and was about to join MIT. Brilliant guy! I recall that in his talk he made an argument that the brain must use digital as well as analog processing. IN a nutshell, he argued that if the brain used purely analog processing, it would be defeated by noise. This came from an electronic cochlear and associated electronics that he built at Bell Labs. A number of analog amplification stages were used until the noise floor threatened to obliterate the signal. The signal was then digitised and the noise floor removed, then more analog stages etc. His argument used statistical noise, so it was nothing to do with electronics per se...
Following on from the previous posts, as to why this has taken so long to develop, there are 2 basic reasons: 1. It is not easy to make SOI wafers! In the SIMOX process, (see previous post), it took years to figure out how to reduce the defect density to acceptable levels. 2. SOI devices are fundamentally different to 'normal' devices in that they may partially or fully deplete the top silicon layer of charge carriers. This does not occur when the silicon device layer is the thickness of an entire wafer! Practically, this means that the device modellers had to go back to square one and produce entirely new models for how the devices really worked, and it took IBM some years to learn how to design transistors on SOI. So it's really quite an achievement, and not just a small incremental change. - r.
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I saw a talk by one of the authors, Rahul Sarpeshkar, who had just finished a postdoc at Bell Labs and was about to join MIT. Brilliant guy! I recall that in his talk he made an argument that the brain must use digital as well as analog processing. IN a nutshell, he argued that if the brain used purely analog processing, it would be defeated by noise. This came from an electronic cochlear and associated electronics that he built at Bell Labs. A number of analog amplification stages were used until the noise floor threatened to obliterate the signal. The signal was then digitised and the noise floor removed, then more analog stages etc. His argument used statistical noise, so it was nothing to do with electronics per se...
Following on from the previous posts, as to why this has taken so long to develop, there are 2 basic reasons: 1. It is not easy to make SOI wafers! In the SIMOX process, (see previous post), it took years to figure out how to reduce the defect density to acceptable levels. 2. SOI devices are fundamentally different to 'normal' devices in that they may partially or fully deplete the top silicon layer of charge carriers. This does not occur when the silicon device layer is the thickness of an entire wafer! Practically, this means that the device modellers had to go back to square one and produce entirely new models for how the devices really worked, and it took IBM some years to learn how to design transistors on SOI. So it's really quite an achievement, and not just a small incremental change. - r.