Logic Gates

Three main basic types of digital logic gate, the AND Gate, the OR Gate and the NOT Gate. And also  we have seen that each gate has an opposite or complementary form of itself in the form of the NAND Gate, the NOR Gate, and that any of these individual gates can be connected together to form more complex Combination Logic circuits.

In Digital Electronics both the NAND gate and the NOR gate can both be classed as “Universal” gates as they can be used to construct any other gate type. In fact, any combination circuit can be constructed using only two or three input NAND or NOR gates.

Digital Logic Gates can be made from discrete component like Resistors, Transistors andDiodes to form RTL (resistor-transistor logic) or DTL (diode-transistor logic) circuits, but today’s modern digital 74xxx series integrated circuits are manufactured using TTL (transistor-transistor logic) based on NPN bipolar transistor technology or the much faster and low power CMOS based MOSFET transistor logic used in the 74Cxxx, 74HCxxx, 74ACxxx and the 4000 series logic chips.

Standard Logic Gates