Tunable resonant inductive coil systems for wireless power transfer and near field communications

A tunable resonant inductive coil system, consisting of:

• a resonant circuit comprising an alternating current (AC) voltage source;
• a barium strontium titanate (BST) tunable capacitor coupled in series with a first terminal of the AC voltage source;
• a coil coupled in series with the first terminal of the AC voltage source;
• and a return line coupling the coil with one of a second terminal of the AC voltage source or a ground;
• wherein the resonant circuit is configured to adjust between a first configuration comprising a first resonant frequency and a second configuration comprising a second resonant frequency.

A method of use of a tunable resonant inductive coil system, comprising:

• providing an electrical circuit, the electrical circuit comprising a barium strontium titanate (BST) tunable capacitor electrically coupled in series with a coil;
• in response to the electrical circuit receiving a control signal at the BST tunable capacitor, adjusting a capacitance of the BST tunable capacitor to adjust a resonant frequency of the electrical circuit between a first resonant frequency configured to be used for wireless power transfer and a second resonant frequency configured to be used for near field communication (NFC);
• and using the coil for both the first resonant frequency and the second resonant frequency;
• a second BST tunable capacitor coupled in series with the coil.