Dynamic voltage scaling is a
power management technique in
computer architecture
In computer engineering, computer architecture is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a more detailed level, the ...
, where the voltage used in a component is increased or decreased, depending upon circumstances. Dynamic voltage scaling to increase voltage is known as overvolting; dynamic voltage scaling to decrease voltage is known as undervolting. Undervolting is done in order to
conserve power, particularly in
laptops and other mobile devices, where energy comes from a battery and thus is limited, or in rare cases, to increase reliability. Overvolting is done in order to support higher frequencies for performance.
The term "overvolting" is also used to refer to increasing static operating voltage of
computer components to allow operation at higher speed (
overclocking).
Background
MOSFET-based digital circuits operate using voltages at circuit nodes to represent logical state. The voltage at these nodes switches between a high voltage and a low voltage during normal operation—when the inputs to a
logic gate
A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic ga ...
transition, the transistors making up that gate may toggle the gate's output.
At each node in a circuit is a certain amount of
capacitance
Capacitance is the capability of a material object or device 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 a ...
. Capacitance can be thought of as a measure of how long it takes for a given current to produce a given voltage change. The capacitance arises from various sources, mainly transistors (primarily
gate capacitance and
diffusion capacitance) and wires (
coupling capacitance). Toggling a voltage at a circuit node requires charging or discharging the capacitance at that node; since currents are related to voltage, the time it takes depends on the voltage appl