Patent ID: 8772909

Claim:
An apparatus comprising: a substrate for supporting circuitry and having a plurality of parallel conductive layers separated by insulation; a region formed in the substrate having an upper conductive shield formed in a second conductive layer of the substrate and a lower conductive shield formed in a fifth conductive layer of the substrate, a transformer formed in the region between the upper conductive shield and lower conductive shield and including a primary winding formed in a third conductive layer of the substrate and a secondary winding formed in a fourth conductive layer of the substrate; the region providing space for a magnetic field coupling the windings; a first high frequency oscillator circuit having an input for receiving an input signal, the first oscillator circuit being connected to excite the primary winding at a first frequency in response to the input signal; a first detector circuit coupled to the secondary winding, having a first output, being adapted to selectively sense the first frequency, and being configured to provide an output signal via the first output in response to the first oscillator exciting the primary winding; and encapsulation material covering the electronic components and at least a portion of an upper surface of the substrate.