Device and method for generating an electrical power supply in an electronic system with a variable reference potential

An apparatus for touch and proximity detection, comprising:

• an integrated circuit including:
• a first electronic system, electrically referenced to a guard potential, configured for capacitively detecting one or more objects at one or more capacitive electrodes;
• and
• a second electronic system, distinct from the first electronic system and electrically referenced to a ground potential, and connected to the first electronic system by decoupling circuitry, wherein the ground potential is different from the guard potential;
• and
• excitation circuitry connected to the guard and ground potentials so as to impose an AC voltage difference between these potentials,
• wherein:
• the decoupling circuitry is configured for communicatively coupling the first electronic system and the second electronic system while maintaining isolation between the guard potential and the ground potential, and
• the excitation circuitry comprises:
• an AC voltage supply source referenced to the ground potential and configured for generating an AC voltage;
• and
• voltage supply circuitry referenced to the guard potential and configured for receiving the AC voltage from the AC voltage supply source and generating a supply voltage for the first electronic system referenced to the guard potential.