Unit 7
Unniversal Gates and Physics
of Integrated Circuits (ICs)
Gates
, Logic gates
The complex logical operations performed by any digital instrument, be it a simple
digital voltmeter or a sophisticated computer, are based on a system of symbolic
concepts known as boolean algebra, named after George Boole, who began
publishing the algebra of logic in 1847.
In a digital instrument, these symbolic concepts are implemented by means of
electronic circuits called logic circuits or gates.
RUDIMENTS OF BOOLEAN ALGEBRA
The three basic logic operations of boolean algebra are named AND, OR, and
NOT.
1. AND Operation
Consider two switches A and B wired in series with
a battery and a load resistor 𝑹 as in Fig. 1 . Current
FIGURE 1 Implementation of the AND
will flow if both switches A and B are closed. These logic function with two manual
switches perform the AND operation, which in switches. Truth Table
symbolic logic is represented as
𝑨 . 𝑩 = 𝑻 or simply 𝑨𝑩 = 𝑻
The statement above reads: If A and B are closed,
transmission will occur.
If condition A is satisfied (is true) and at the same time condition B is satisfied, then
the desired result will be obtained and the output will be true (T).
, Boolean Algebra
2. OR Operation
Truth Table
If two switches A and B are wired in parallel
with each other, and this parallel combination
is then connected in series with a battery and
a load resistor R, as in Fig. 2, transmission will Figure 2. Implementation of
occur if either A or B is closed. The circuit will the OR logic function with two
perform the OR operation, which in symbolic manual switches.
logic is represented as This statement means that the desired result is true
𝑨+𝑩=𝑻 (𝟐) if either condition A or condition B or both are true.
3. NOT Operation
Truth Table
The NOT operation simply inverts the logic condition. It is written as A,
which reads NOT A. Thus if A stands for "the sun will shine tomorrow,"
then A stands for "the sun will not shine tomorrow." As an example of a
truth table using the NOT concept, consider the following boolean
equation.
𝑨·𝑩= 𝑻 (𝟑)
Equation 3 means that if condition A is satisfied and at the same time condition B is
not satisfied, the output will be true.
, Boolean Algebra
ELECTRONIC LOGIC CIRCUITS
A logic circuit is one with an output signal that is the logical function of the inputs.
These circuits are called gates.
AND Gate OR Gate NOT Gate
Universal gates:
Two gates that are often used in integrated
circuits (IC) are the NAND and the NOR gates, called the
Universal Gates.
NAND Gate NOR Gate
Unniversal Gates and Physics
of Integrated Circuits (ICs)
Gates
, Logic gates
The complex logical operations performed by any digital instrument, be it a simple
digital voltmeter or a sophisticated computer, are based on a system of symbolic
concepts known as boolean algebra, named after George Boole, who began
publishing the algebra of logic in 1847.
In a digital instrument, these symbolic concepts are implemented by means of
electronic circuits called logic circuits or gates.
RUDIMENTS OF BOOLEAN ALGEBRA
The three basic logic operations of boolean algebra are named AND, OR, and
NOT.
1. AND Operation
Consider two switches A and B wired in series with
a battery and a load resistor 𝑹 as in Fig. 1 . Current
FIGURE 1 Implementation of the AND
will flow if both switches A and B are closed. These logic function with two manual
switches perform the AND operation, which in switches. Truth Table
symbolic logic is represented as
𝑨 . 𝑩 = 𝑻 or simply 𝑨𝑩 = 𝑻
The statement above reads: If A and B are closed,
transmission will occur.
If condition A is satisfied (is true) and at the same time condition B is satisfied, then
the desired result will be obtained and the output will be true (T).
, Boolean Algebra
2. OR Operation
Truth Table
If two switches A and B are wired in parallel
with each other, and this parallel combination
is then connected in series with a battery and
a load resistor R, as in Fig. 2, transmission will Figure 2. Implementation of
occur if either A or B is closed. The circuit will the OR logic function with two
perform the OR operation, which in symbolic manual switches.
logic is represented as This statement means that the desired result is true
𝑨+𝑩=𝑻 (𝟐) if either condition A or condition B or both are true.
3. NOT Operation
Truth Table
The NOT operation simply inverts the logic condition. It is written as A,
which reads NOT A. Thus if A stands for "the sun will shine tomorrow,"
then A stands for "the sun will not shine tomorrow." As an example of a
truth table using the NOT concept, consider the following boolean
equation.
𝑨·𝑩= 𝑻 (𝟑)
Equation 3 means that if condition A is satisfied and at the same time condition B is
not satisfied, the output will be true.
, Boolean Algebra
ELECTRONIC LOGIC CIRCUITS
A logic circuit is one with an output signal that is the logical function of the inputs.
These circuits are called gates.
AND Gate OR Gate NOT Gate
Universal gates:
Two gates that are often used in integrated
circuits (IC) are the NAND and the NOR gates, called the
Universal Gates.
NAND Gate NOR Gate
