An Interview with Hans Camenzind


Oral History – Hans Camenzind



What patents are related to the 555?

There are no patents on the 555.  Signetics did not want to apply for a patent.  You see, the situation with patents in Silicon Valley in 1970 was entirely different than it is now. Everybody was stealing from everybody else.  I designed the 555 Signetics produced it, and six months, or before a year later, National had it, Fairchild had it, and nobody paid any attention to patents.   The people at Signetics told me they didn’t want to apply for a patent, because what would happen if they tried to enforce that patent, is the people from Fairchild would come back with a Manhattan-sized telephone book and say “These are our patents, now let’s see what you’re violating”. It was a house of cards – if you blew on it, the whole thing collapsed.  It took about ten years to change. I guess it was some new companies that didn’t have ancient history and did have a strong patent, and started enforcing, and that changed to whole situation.  It is very intense now. The same thing – I have a patent on the phase locked loop, and that would have been a very strong patent, but no enforcement. 


Hans, thank you for taking the time for this very informative interview on such a important aspect of IC history. Any final comments on why the 555 design has been so resilient for so long?

The thing is that this is not a good design (the 555).  I had a few years of experience, I’d say about five years, but I had no teacher, and I had to learn it by myself.






Oral History – Hans Camenzind



You know it was really the beginning of design, so looking at it now, I would say “I wouldn’t do it like that again”.  But nobody has actually changed it -  it is still the same.  They have shrunk it, they shrunk the dimensions.  It was a 10 micrometer design, that was the standard size.  You could make it in four (micrometers) now.  This is more die per wafer, but nobody has changed the arrangement or the schematic. 


As a timer, you know, you trigger it and it runs for a certain time, it is very good.  It has a temperature coefficient of like 23 parts per million.   Over a large temperature range, that’s like  .1 %.  Its very stable.  In free running mode, as an oscillator, its not so good, about 150 parts per million. And that you could improve down to about 10 ppm. So you could make an improved product.  I’m amazed and stunned that in 30 years, somebody hasn’t looked at the schematic and said, “I can make this better”, so for the same area and same cost, and then they have a better product.  Nobody has done that. 




Camenzind Historic Audio Recordings









COPYRIGHT © 2004 by Jack Ward.  All Rights Reserved.