Correction: Prob. #6 implements the function, f = ab+c. This can be
rewritten in terms of the inputs shown as f = ~((~a+~b)~c). My apologies.

Neal N. Oza

On 4/11/08, Neal Oza <nealoza@u.northwestern.edu> wrote:
>
> The circuit in problem 6 does use 6 transistors, but that does not
> implement a 3-input OR gate. Rather, it implements ~a~b+~c. But what that
> circuit doesn't show you is that if you want to use any of those input
> signals (~a, ~b, ~c), you need to use more transistors to invert the
> original signals (a, b, c). Remember, for problem 8 it explicitly states,
> "For this problem, please do not assume that you can complement inputs for
> zero cost."
>
> Hopefully this helps.
>
> Neal N. Oza
>
> On 4/11/08, Byron Cheng <Byron@u.northwestern.edu> wrote:
> >
> > I'm looking over this question again and I'm still having problems
> > understanding why three NMOS and three PMOS transistors don't work. For
> > instance, isn't the circuit in problem 6 made up only of NMOS and PMOS
> > transistors? I thought that even though they aren't good at
> > transmitting
> > both types of signals, because they are used in conjunction it works
> > out?
> >
> > I know it's late, but I'd appreciate any clarification. Thanks
> >
> > _______________________________________
> >
> > Byron Cheng
> > byron@u.northwestern.edu
> > byroncheng@gmail.com
> >
> > -----Original Message-----
> >
> > >> It seems like problem 8 is very simple to do with three of each. Am
> > I
> > missing something?
> > >>
> > >> Jeremy
> >
> > Remember that NMOS and PMOS aren't good at transmitting both high and
> > low
> > voltages. Each is only good for one of the two. Additionally, remember
> > that you cannot assume access to complemented inputs for this problem.
> >
> > -- David
> >
> >
>
>
> --
> Neal N. Oza
> Graduate Student Researcher
> Northwestern University
> nealoza@u.northwestern.edu

-- 
Neal N. Oza
Graduate Student Researcher
Northwestern University
nealoza@u.northwestern.edu