[time-nuts] The Original Time Nut
attila at kinali.ch
Sun Feb 24 16:46:47 EST 2008
On Sun, 24 Feb 2008 12:20:33 -0500
Bob Paddock <bob.paddock at gmail.com> wrote:
> On Saturday 23 February 2008 11:15:35 pm Neville Michie wrote:
> > As it is we have a very strongly established tradition of "locking"
> > and "impulsing" in all the escapements of clocks, very similar to the zero
> > voltage, transition to high, and ultimate return to zero, that we have to
> > trigger counters and the like.
> What kind of never-before-made clock can be made
> with ALD's Zero Threshold MOSFETs?
Threshold voltage alone doesn't say anything. V_th can be
easily controlled with the doping levels of the semiconductor.
Thus, there were FETs with arbitrary V_th (positve and negative)
available for ages. Though, what is problematic is to get a
small difference of V_GS between fully off and fully on. This
used to be in the range of 10-20V not too long ago and is nowadays
around 1V for low power MOSFETs.
Have a look at the datasheet. They specify an R_DS(on) of 104k
at 0.0V. I don't know with what kind of circuits you work, but
for me that is pretty much OFF as it can be. Only at an
V_GS of 4V you get a reasonable R_DS(on) of 500R, which is still
a lot, even for a small signal transistor.
There are also lots of interesting data missing from the datasheet,
like the actual I_DS versus V_DS and V_GS, frequency response,
capacitance values dependend on voltage levels, etc pp.
If you want to build cool new circuits, you rather stick to
the old fashioned, but proven FETs with full data available.
The true CS students do not need to know how to program.
They learn how to abstract the process of programming to
the point of making programmers obsolete.
-- Jabber in #holo
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