A directional coupler includes capacitive elements electrically connected to a coupled port and an isolated port, respectively, for a coupled line on a chip (on-chip). The capacitive elements serve as matching capacitive elements and may be MIM (Metal Insulator Metal) capacitors on a substrate. A first end of a first of the capacitive elements is connected between the coupled port and the coupled line and a second end is grounded. A first end of a second of the capacitive elements is connected between the isolated port and the coupled line and a second end is grounded.