A directional coupler that provides directional coupling and an impedance transformation is disclosed. In one embodiment, the directional coupler includes a low pass filter having a filter inductor that is coupled between an input port and an output port and a filter capacitor coupled between the output port and ground. The directional coupler also includes detector circuitry wherein the filter inductor is magnetically coupled to a detector inductor in the detector circuitry such that current passing through the filter inductor generates a detector current through the detector inductor. Furthermore, the low pass filter and the detector circuitry cooperate to transform a first impedance presented at the output port to a second impedance presented at the input port. Accordingly, the filter inductor is used in the low pass filter to provide an impedance transformation so as to operate with the detector circuitry to provide a detector current for directional coupling.