dualsupply

dualsupply is a power-supply configuration that provides two opposite polarity rails with a common return. In its typical form, the outputs are a positive rail (+V) and a negative rail (-V) referenced to ground, enabling signals to swing around zero volts. This symmetry is advantageous for many analog circuits, especially those dealing with bipolar signals or needing headroom on both sides of zero.

There are several ways to realize a dual supply. A center-tapped transformer with rectification and regulation can generate +V and -V from a single source. Alternatively, two separate regulators or switching regulators can furnish the rails, sometimes with a virtual ground or rail splitter to create a stable midpoint. Some designs use a single supply and an artificial reference to emulate a negative rail, but a true dual supply provides independent regulation for each rail.

Common voltage pairs include ±5 V, ±12 V, and ±15 V, commonly used in operational amplifiers, instrumentation, audio equipment, and test benches. Dual supplies facilitate simpler biasing of bipolar circuits and can improve linearity and dynamic range compared to single-supply designs that rely on virtual ground.

Advantages of a dual supply include symmetric headroom, straightforward biasing for many analog circuits, and better performance for precision amplifiers. Limitations involve additional components, higher cost, potential ground-loop and regulation challenges, and increased heat dissipation for the regulators.

See also: single-supply systems, virtual ground, rail splitter, and dual-power-supply units.