High performance inductive sensing all digital phase locked loop

A system comprising:

• a sensor;
• a first capacitor;
• and
• an integrated circuit comprising a first terminal and a second terminal, wherein the first capacitor and the sensor are coupled in parallel across the first terminal and the second terminal, wherein the integrated circuit comprises an inductance-to-digital converter (LDC) comprising a digital control loop and a digital filter to measure an inductance change of the sensor and convert the inductance change to a digital value, wherein the sensor forms an oscillator in the digital control loop, wherein the digital control loop is configured to maintain a fixed frequency in the sensor by selectively coupling the first capacitor to the sensor, wherein an output of the digital control loop is proportional to the inductance change of an inductive element in the sensor.

A method comprising:

• measuring, by an integrated circuit a first signal having a sensor frequency of a sensor coupled to the integrated circuit, wherein the sensor is part of a digital control loop of an inductance-to-digital converter (LDC) of the integrated circuit;
• maintaining, by the integrated circuit, a fixed frequency in the sensor by coupling a first capacitor to the sensor using an output of the digital control loop;
• and
• digitizing, by the integrated circuit, the output of the digital control loop to a digital value, wherein the output of the digital control loop is proportional to an inductance change of the sensor.