The AND gate - Digital Logic gates
Gates are what make many of ICs, the two popular
families are the 40xx CMOS and the 74xx TTL . Now 40xx come in
74HCT40xx flavors which approach the quality of an ideal gate.
Entire circuits with Gates can also be also be burnt
into PLDs, FPGAs and CPLDs just like you burn your CDROM. Gates can
also be implemented in assembly language which a microcontroller like
8051 will understand and execute. Hardware gate circuit will operate in
real time, propagation
delay of nano seconds will be there due to parasitic gate capacitance
or FET switching times. Software Gates using microcontroller and code
will depend on both propagation
delay of semiconductor, CPU clock speed and BUS width.
AND Gate Simulation
This gate ANDs the two inputs A and B, The Output is
high only if A AND B both are high. There may be a AND gate with many
inputs, only if all inputs are high the output will be high.
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enabled
to try out the
demo of the gates below.
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A
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Q
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 |
 |
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B |
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Toggle the red buttons above to apply a
'high' or 'low' to inputs A and B and watch the output Q.
Truth table
| A
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B
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Q
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0
|
0 |
0
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| 0 |
1 |
0 |
| 1 |
0 |
0 |
1
|
1 |
1
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The AND gates can be built with diodes and transistors if you want to
do it on your own. Then read more on how to do it here at play-hookey's digital
section and Logic families.
More on TTL and CMOS here at Logic
Family Voltage Translation.
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