A range of electronic devices that is made by the same manufacturing technique and provides a number of logic functions. The range includes logic gates, flip-flops, and counters. Families in common use are ECL and TTL, which are based on bipolar transistors, and the NMOS and CMOS families, which are based on MOSFETs.
Logic families vary as regards switching speed, propagation delay, and power dissipation, although developments in the fabrication technology of the different families often improve these characteristics. A member of a logic family whose output changes state typically within a few nanoseconds (10−9 second) is considered a high-speed logic device. These devices are also characterized by short propagation delays, also in the order of a few nanoseconds. A particular family is characterized by its delay-power product, a figure of merit that is frequently quoted in catalogues. See also logic circuit.