What is "direct coupling"

n. Energy transfer achieved by means of physical contact, i.e., coupling other than inductive or capacitive coupling.

In electronics, direct coupling or DC coupling (also called conductive coupling) is the transfer of electrical energy by means of physical contact via a conductive medium, in contrast to inductive coupling and capacitive coupling. It is a way of interconnecting two circuits such that, in addition to transferring the AC signal (or information), the first stage also provides DC bias to the next. Thus, there is no need for a DC blocking capacitor to be used in order to interconnect the circuits. Conductive coupling passes the full spectrum of frequencies including direct current.

Such coupling may be achieved by a wire, resistor, or common terminal, such as a binding post or metallic bonding.