A physical or idealized component implementing a fixed Boolean function on one or more input bits. For example, an AND gate outputs one exactly when both input bits are one. A Boolean circuit connects logic gates; circuit size counts components and circuit depth measures the longest chain of dependencies.
A two-input logic gate whose output is one exactly when its two input bits agree. Its Boolean function is , equivalently . This follows by considering the two cases in which inputs are equal. It implements logical equivalence of the input truth values.
The number of load inputs driven by one output of a logic gate. A large fan-out increases the capacitive load and can increase propagation delay; the allowable number also depends on the logic technology and input characteristics.
A logic gate computing the logical negation of the logical conjunction of its inputs. Thus . It implements a logical disjunction of complemented inputs by De Morgan laws.
