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A CMOS transistor NAND element. V dd denotes positive voltage.. In CMOS logic, if both of the A and B inputs are high, then both the NMOS transistors (bottom half of the diagram) will conduct, neither of the PMOS transistors (top half) will conduct, and a conductive path will be established between the output and Vss (ground), bringing the output low.
The NAND gate has the property of functional completeness, which it shares with the NOR gate. That is, any other logic function (AND, OR, etc.) can be implemented using only NAND gates. [2] An entire processor can be created using NAND gates alone. In TTL ICs using multiple-emitter transistors, it also requires fewer transistors than a NOR gate.
Together with the AND gate and the OR gate, any function in binary mathematics may be implemented. All other logic gates may be made from these three. [3] The terms "programmable inverter" or "controlled inverter" do not refer to this gate; instead, these terms refer to the XOR gate because it can conditionally function like a NOT gate. [1] [3]
A logic circuit diagram for a 4-bit carry lookahead binary adder design using only the AND, OR, and XOR logic gates. A logic gate is a device that performs a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output.
Diagram showing a way of making a logical inverter (NOT gate) from a NAND gate. Date: 22 December 2008: Source: Own work: Author: Inductiveload: Permission (Reusing this file) Own work, all rights released (Public domain)
CMOS inverter (a NOT logic gate). Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss ", / s iː m ɑː s /, /-ɒ s /) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. [1]
An XNOR gate can be implemented using a NAND gate and an OR-AND-Invert gate, as shown in the following picture. [3] This is based on the identity ¯ (¯) ¯ An alternative, which is useful when inverted inputs are also available (for example from a flip-flop), uses a 2-2 AND-OR-Invert gate, shown on below on the right.
Schematic of basic two-input DTL NAND gate. R3, R4 and V− shift the positive output voltage of the input DL stage below the ground (to cut off the transistor at low input voltage). Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic.