Current mirror self-capacitance measurement

A computer-readable non-transitory storage medium embodying logic configured when executed to:

• apply a first current to a capacitance of a touch sensor, the first current having a first magnitude, the first magnitude being the magnitude of the current actually applied to the capacitance, the application of the first current to the capacitance modifying a voltage at the capacitance from a reference voltage level to a first pre-determined voltage level;
• apply a second current to an integration capacitor, the second current being proportional to the first current, the application of the second current to the integration capacitor modifying a voltage at the integration capacitor from the reference voltage level to a first charging voltage level;
• apply a third current to the capacitance, the application of the third current to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to the reference voltage level;
• apply a fourth current to the integration capacitor, the fourth current being proportional to the third current, the application of the fourth current to the integration capacitor modifying the voltage at the integration capacitor from the first charging voltage level to a second charging voltage level;
• and
• determine whether a touch input to the touch sensor has occurred based on the second charging voltage level.

A device comprising:

• a measurement circuit;
• and
• a computer-readable non-transitory storage medium coupled to the measurement circuit and embodying logic configured when executed to:
• apply a first current to a capacitance of a touch sensor, the first current having a first magnitude, the first magnitude being the magnitude of the current actually applied to the capacitance, the application of the first current to the capacitance modifying a voltage at the capacitance from a reference voltage level to a first pre-determined voltage level;
• apply a second current to an integration capacitor the second current being proportional to the first current, the application of the second current to the integration capacitor modifying a voltage at the integration capacitor from the reference voltage level to a first charging voltage level;
• apply a third current to the capacitance, the application of the third current to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to the reference voltage level;
• apply a fourth current to the integration capacitor, the fourth current being proportional to the third current, the application of the fourth current to the integration capacitor modifying the voltage at the integration capacitor from the first charging voltage level to a second charging voltage level;
• and
• determine whether a touch input to the touch sensor has occurred based on the second charging voltage level.