GaAs CMOS in Cray-3 ?

[David R. Greenberg]

In article <3892 at portia.Stanford.EDU> Michael Brooks writes:

>More likely there is a set of ntype MESFETs that have "complementary"
>like threshold voltages.  When one is on, the other is off (basically
>one is an enhancment mode FET and the other is a depletion mode).

This is not possible.  The only difference between enhancement and depletion
mode devices is the sign of the threshold voltage.  For both types of devices,
the gate to source bias must be greater than the threshold voltage for the
device to be on.  This is in contrast to a p-type device in which the
gate to source bias must be less than the threshold voltage.

Thus, for n-type devices, the device with the lower threshold voltage can
be on while the other is off, but not vice versa.

- David