Gate equivalent

A gate equivalent (GE) stands for a unit of measure which allows to specify manufacturing-technology-independent complexity of digital electronic circuits. For today's CMOS technologies, the silicon area of a two-input drive-strength-one NAND gate usually constitutes the technology-dependent unit area commonly referred to as gate equivalent. A specification in gate equivalents for a certain circuit reflects a complexity measure, from which a corresponding silicon area can be deduced for a dedicated manufacturing technology.

In digital circuit design, a dedicated standard cell library is employed for each manufacturing technology (e.g., CMOS). The standard cell library comprises many different logic gates, for example a NAND gate. For each logical type of logic gate, e.g., a two-input NAND, there usually exist different physical realizations in the standard cell library, for instance with different output drive strengths.

Basically, a two-input drive-strength-one NAND gate in CMOS technology consists of four transistors. If higher output drive strength is required, an additional output driver stage of four transistors is added.

References

• Digital Integrated Circuit Design: From VLSI Architectures to CMOS Fabrication, Hubert Kaeslin, Cambridge University Press, 2008

See also

• Logic family
• NMOS logic
• MOSFET
• Fanout
• FO4
• Boolean logic