CMOS NOR Gate
CMOS NOR gate
A CMOS NOR gate circuit uses four MOSFETs just like the NAND gate, except that its transistors are diifferently arranged. Instead of two paralleled sourcing (upper) transistors connected to Vdd and two series-connected sinking (lower) transistors connected to ground, the NOR gate uses two series-connected sourcing transistors and two parallel-connected sinking transistors like this:
As with the NAND gate, transistors Q1 and Q3 work as a complementary pair, as do transistors Q2 and Q4. Each pair is controlled by a single input signal. If either input A or input B are "high" (1), at least one of the lower transistors (Q3 or Q4) will be saturated, thus making the output "low" (0). Only in the event of both inputs being "low" (0) will both lower transistors be in cutoff mode and both upper transistors be saturated, the conditions necessary for the output to go "high" (1).
This behavior, of course, defines the NOR logic function.
Keywords :
Nand,
Gate,
Cmos,
NOR,
CMOS-NORgates,
Logiv Gate,
Create,
High,
Low,
Logic
Writer : delon |
26 Nov 2006 Mon
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