Buffer-reference self-capacitance measurement

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

• set a voltage at an integration capacitor to an integration-reference voltage level;
• modify the voltage at the integration capacitor from the integration-reference voltage level to a first charging voltage level, the modification of the voltage at the integration capacitor resulting from application of a first amount of charge to the integration capacitor, the first amount of charge being proportional to an amount of charge modifying a voltage at a capacitance of a touch sensor from a reference voltage level to a first pre-determined voltage level;
• modify the voltage at the integration capacitor from the first charging voltage level to a second charging voltage level, the modification of the voltage at the integration capacitor resulting from application of a second amount of charge to the integration capacitor, the second amount of charge being proportional to an amount of charge modifying a voltage at the capacitance from the first pre-determined voltage level to a second pre-determined voltage level;
• determine a first difference between the integration-reference voltage level and the first charging voltage level and a second difference between the first charging voltage level and the second charging voltage level;
• and
• determine whether a touch input to the touch sensor has occurred based on the first and second differences.

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:
• set a voltage at an integration capacitor to an integration-reference voltage level;
• modify the voltage at the integration capacitor from the integration-reference voltage level to a first charging voltage level, the modification of the voltage at the integration capacitor resulting from application of a first amount of charge to the integration capacitor, the first amount of charge being proportional to an amount of charge modifying a voltage at a capacitance of a touch sensor from a reference voltage level to a first pre-determined voltage level;
• modify the voltage at the integration capacitor from the first charging voltage level to a second charging voltage level, the modification of the voltage at the integration capacitor resulting from application of a second amount of charge to the integration capacitor, the second amount of charge being proportional to an amount of charge modifying a voltage at the capacitance from the first pre-determined voltage level to a second pre-determined voltage level;
• determine a first difference between the integration-reference voltage level and the first charging voltage level and a second difference between the first charging voltage level and the second charging voltage level;
• and
• determine whether a touch input to the touch sensor has occurred based on the first and second differences.