Capacitive coupling

Capacitive coupling is the transfer of energy within an electrical network or between distant networks by means of displacement currents induced by existing electric fields between circuit(s) nodes. This coupling can have an intentional or accidental effect. In its simplest implementation, capacitive coupling is achieved by placing a capacitor in series between two nodes. In its general form the coupling is described by a capacitance matrix C_ij. Where C_ii are self-capacitance coefficients and C_ij i≠j are mutual capacitance coefficients.

For Wireless Power Systems, the simplest model for capacitive coupling involves two self-capacitances and one mutual capacitance.

Use in analog circuits

In analog circuits, a coupling capacitor is used to connect two circuits such that only the AC signal from the first circuit can pass through to the next while DC is blocked. This technique helps to isolate the DC bias settings of the two coupled circuits. Capacitive coupling is also known as AC coupling and the capacitor used for the purpose is also known as a DC-blocking capacitor.