electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

, gate capacitance is the

capacitance Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related ...

of the gate terminal of a

field-effect transistor The field-effect transistor (FET) is a type of transistor that uses an electric field to control the current through a semiconductor. It comes in two types: junction FET (JFET) and metal-oxide-semiconductor FET (MOSFET). FETs have three termi ...

(FET). It can be expressed as the absolute capacitance of the gate of a transistor, or as the capacitance per unit area of an

integrated circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...

technology, or as the capacitance per unit width of minimum-length transistors in a technology. In generations of approximately Dennard scaling of metal-oxide-semiconductor FETs (MOSFETs), the capacitance per unit area has increased inversely with device dimensions. Since the gate area has gone down by the square of device dimensions, the gate capacitance of a transistor has gone down in direct proportion with device dimensions. With Dennard scaling, the capacitance per unit of gate width has remained approximately constant; this measurement can include gate–source and gate–drain overlap capacitances. Other scalings are not uncommon; the voltages and gate oxide thicknesses have not always decreased as rapidly as device dimensions, so the gate capacitance per unit area has not increased as fast, and the capacitance per transistor width has sometimes decreased over generations. The intrinsic gate capacitance (that is, ignoring fringing fields and other details) for a silicon-dioxide-insulated gate can be calculated from thin-oxide capacitance per unit area as: :

C_\mathrm = A_\mathrmC_\mathrm

where: * is the gate area *

C_\mathrm = \frac

is the thin-oxide capacitance per unit area, where ** is the

relative permittivity The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the vacuum permittivity, electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric co ...

of silicon dioxide ** is the

vacuum permittivity Vacuum permittivity, commonly denoted (pronounced "epsilon nought" or "epsilon zero"), is the value of the absolute dielectric permittivity of classical vacuum. It may also be referred to as the permittivity of free space, the electric const ...

** is the oxide thickness.

References

Semiconductor technology {{tech-stub