AND gate
The AND gate
is a basic digital logic gate that implements
logical conjunction - it behaves according to the truth table to the right. A
HIGH output (1) results only if both the inputs to the AND gate
are HIGH (1). If neither or only one input to the AND gate
is HIGH, a LOW output result
1.
a Boolean operator that gives the
value one if and only if all the operands are one, and otherwise has a value of
zero.
0.
a circuit that produces an output signal
only when signals are received simultaneously through all input connections.
Transistor AND Gate
The use of transistors
for the construction of logic gates
depends upon their utility as fast switches.
When the base-emitter diode is turned on enough to be driven into saturation, the collector voltage with respect to
the emitter may be near zero and can be used to construct gates for the TTL logic family. For the AND logic, the transistors are in series and both
transistors must be in the conducting state to drive the output high.
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The use
of transistors
for the construction of logic gates
depends upon their utility as fast switches.
When the base-emitter diode is turned on enough to be driven into saturation, the collector voltage with respect
to the emitter may be near zero and can be used to construct gates for the TTL logic family. For the OR logic, the transistors are in parallel and
the output is driven high if either of the transistors is conducting.
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NOR Gate single Transistor
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The use of transistors for the construction of logic gates depends upon their utility as fast switches. When the base-emitter diode is turned
on enough to be driven into saturation,
the collector voltage with respect to the emitter may be near zero and can be
used to construct gates for the TTL logic family.
In this alternative way to achieve NOR
logic, only one transistor is used with the two inputs tied to its base
through resistors. If either or both of the inputs is high, the output is
driven low
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