Unformatted text preview: Binary Logic Gates
CHAPTER 3 3-inputAND gate Fig. 3‘20 Substituting NAND gates. gates would be wired to perform the logic
function. The chart in Fig. 3-20 need not be
memorized. but it may he referred to as
needed in your future work in digital elec-
tronics. 3-9 GATES WITH
MORE INPUTS Until now we have used gates that have had
only two or less inputs. But often we shall
need gates with more than iust two inputs.
Figure 3-21tal shows a 3-input AND gate.
The Boolean expression For the 3-input AND gate is A -B -C = Y, as illustrated in Fig.
3-21(b). All the possible combinations of
inputs A, B, and C are given in the truth table
in Fig. 3-21(c); the outputs for the 3-input
AND gate are tabulated in the right column of
the truth table. Notice that with three inputs
the possible combinations in the truth table
have increased to eight. How could you produce a 3-input AND
gate as illustrated in Fig. 3-21 if you have only
2-input AND gates available? The solution is
given in Fig. 3-2.2(a). Note the wiring of the
2-input AND gates on the right side of the dia-
gram to form a 3-input AND gate. Figure 17 ...
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- Fall '05