What is a Logic Gate?

Logic gates are basic components on integrated circuits. Simple logic gates can be composed of transistors. The combination of these transistors allows the high and low levels representing the two signals to generate a high or low level signal after passing through them. The high and low levels can represent logical "true" and "false" or 1 and 0 in binary, respectively, so as to realize logical operations.

Let A and B be input variables

Types of	Aka / short release	Logical function representation	Truth table
NOT	NOT / Inverter: Reverse the high and low states of the input.	A '	Enter A 0 1	Output An 1 0
AND	AND / and gate: When all inputs are high, Only the output will be high.	A * B	Enter AB 0 0 0 1 1 0 1 1	Output AandB 0 0 0 1
NAND	NAND gate: The opposite of AND. When all inputs are high, Only when the output is low.	(A * B) '	Enter AB 0 0 0 1 1 0 1 1	Output AnandB 1 1 1 0
OR	OR gate: When all inputs are low, Only when the output is low.	A + B	Enter AB 0 0 0 1 1 0 1 1	Output AorB 0 1 1 1
NOR	NOR gate: Opposite the OR gate. When all inputs are low, Only the output will be high.	(A + B) '	Enter AB 0 0 0 1 1 0 1 1	Output AnorB 1 0 0 0
XOR	XOR gate: The output is low when the inputs are the same, Otherwise it is high.	A'B + AB '	Enter AB 0 0 0 1 1 0 1 1	Output AxorB 0 1 1 0
XNOR	XOR gate: The opposite of an XOR gate. The output is high when the inputs are the same, Otherwise it is low.	AB + A'B '	Enter AB 0 0 0 1 1 0 1 1	Output AxnorB 1 0 0 1

The electronic circuit of the basic logic operation is called a logic gate circuit. In digital circuit relationship applications, gates in logic gate circuits represent circuits with basic logic relationships.

According to the difference of the source device of the internal circuit of the logic gate, we can divide it into three categories. The more commonly used is the CMOS logic gate circuit.

This CMOS logic gate circuit has good application benefits. First of all, its power consumption is relatively low and its application cost is relatively low. Relatively high. The MOS gate circuit is composed of a series of unipolar MOS transistors. It has a relatively simple manufacturing process, low power consumption, high integration, and strong anti-interference ability. It is more suitable for large-scale integrated circuits. Applications.

In practice, MOS gate circuits are divided into different types according to their applications. The application advantages of CMOS circuit are relatively special, its static power consumption is relatively low, its anti-interference ability is strong, its work has high stability, and its switching speed is relatively high, so its application is relatively wide.

In digital circuit applications, a logic gate is a basic logic element. The logic gate is a kind of switch. Under certain conditions, it determines whether the signal is passed or not. In actual operation, we can see that there is a close causal relationship between the input and output of the gate circuit. We call the gate circuit a logic gate circuit, and its basic logic relationship is negation, or, and. ^[1]