capacitor

electronics An electronic device that can store electrical

charge. The charge stored Q in Coulombs is related to the

capacitance C in Farads and the voltage V across the capacitor

in Volts by Q = CV.

The basis of a dynamic RAM cell is a capacitor. They are

also used for power-supply smoothing (or "decoupling"). This

is especially important in digital circuits where a digital

device switching between states causes a sudden demand for

current. Without sufficient local power supply decoupling,

this current "spike" cannot be supplied directly from the

power supply due to the inductance of the connectors and so

will cause a sharp drop in the power supply voltage near the

switching device. This can cause other devices to malfunction

resulting in hard to trace glitches.

(1995-04-12)