Very-large-scale integration

The integration means the absolute number of transistors in an integrated circuit (English integrated circuit IC). The degree of integration results from the integration density ( number of transistors per unit area) and the chip size (area of the IC ).

The degree of integration is also called logical complexity if, instead of transistors logic gates are counted. A gate corresponding to about four transistors, such as are necessary for an unbuffered NAND gate with two inputs in the dominant CMOS technology. Complex logic circuits, such as Field Programmable Gate Arrays ( FPGA), are often not realized internally of individual gates, but, for example, lookup tables. In this case gate equivalents are counted, i.e. the number of logic gates that would be needed to implement this functionality. Information complexity in gate equivalents can be only conditionally compare between manufacturers, as these large data discretions are available.

Degree of integration or logical complexity are very often characterized by terms such as SSI, MSISp, LSI or VLSI ( rarely also ULSI or SLSI ). SI stands for English scale integration, the respective prefix for the degree of integration, such as VLSI stands for english very -large-scale integration. These terms are inconsistently defined and can be found in the literature very different numbers. For processors that consist of more than 500 million transistors (eg AMD Opteron ), these names have become less important.