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# How to design a+(b+c)'+c using CMOS?

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#### seemagoyal44

##### Member level 1
can anybody tell how to design a+(b+c)'+c using cmos

....2nd term b+c)' is nor gate but how to add a+c with nor that i dont understand

Re: cmos layout

seemagoyal44 said:
can anybody tell how to design a+(b+c)'+c using cmos

....2nd term b+c)' is nor gate but how to add a+c with nor that i dont understand

Still there is something wrong...First of all, Why do you call this post 'cmos layout', I really don't understand. Please be more specific.

Re: cmos layout

a+(b+c)'+c=((a+(b+c)'+c)')'=(a'*(b+c)*c')'
(a'*(b+c)*c')' - this is standard equation for cmos digital design. if you want I can draw circuit later...

Re: cmos layout

a+(b+c)'+c = a+(bbar.cbar)+c
Take + as parallel and . as series, so
4 pmos transistors are arranged as shown below

a b c (a in parallel with c and parallel with b and c which are in series)
c

( a+(b+c)'+c ) ḃar= abar.(b+c).cbar

therefore 4 NMOS transistors are arranged as

abar
b and c in parallel (abar in series with (b and c parallel) and these in series with cabr)
cbar

(use CMOS inverter for negation)

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