On Sunday 29 June 2008, John Doty wrote: > You're assuming voltage interfaces. Current interfaces turn > that on its head.
No, but.... > And then there's the trick of grounding an > opamp "output" and getting output current from the power > pins: this illustrates that the direction and discipline > depend on the application, not on the part. An opamp "output" is really usually an "inout". I agree that "the direction and discipline depend on the application". An opamp model that claims the output has direction "output" is probably not adequate for the application you mention. > I read the book you recommended on Verilog-AMS. It misses the > critical idea that mixed signal design is applied physics, > not computer programming. A computer can usually evaluate a > function that you can logically describe, but circuitry is > more restricted, especially if speed, noise, and power are > significant considerations. The top-down design methodology > the authors advocate is almost guaranteed to demand parts > made of unobtainium if applied to challenging requirements. > > > It looks to me that geda has mixed the concepts of > > discipline and direction. > > Yes, but the real problem is the mixing of such clerical > concepts into what is really a set of applied physics issues. Interesting point .. There is nothing keeping you from describing things like a one femtoHertz oscillator or a new CPU with a 100 TeraHertz clock. Building it, on the other hand, might be a little difficult. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user