Excitation Voltages for Touch Sensors

A non-transitory computer-readable medium comprising logic, the logic configured to, when executed by a processor, cause the processor to perform operations comprising:

• applying a first excitation voltage to an electrode of a touch sensor, wherein applying the first excitation voltage to the electrode charges a capacitive node associated with the electrode from a first voltage level to a second voltage level that is greater than the first voltage level;
• determining a first charge measurement, wherein the first charge measurement is associated with a first change from the first voltage level to the second voltage level;
• applying a second excitation voltage to the electrode of the touch sensor, wherein applying the second excitation voltage to the electrode charges the capacitive node from the second voltage level to a third voltage level that is greater than the second voltage level;
• discharging the capacitive node from the third voltage level to a fourth voltage level that is less than the second voltage level;
• determining a second charge measurement, wherein the second charge measurement is associated with a second change from the third voltage level to the fourth voltage level;
• and
• determining a measured charge signal based on the first charge measurement and the second charge measurement;
• wherein the first excitation voltage and the second excitation voltage are each derived from a reference voltage.

A method, comprising:

• applying a first excitation voltage to an electrode of a touch sensor, wherein applying the first excitation voltage to the electrode charges a capacitive node associated with the electrode from a first voltage level to a second voltage level that is greater than the first voltage level;
• determining a first charge measurement, wherein the first charge measurement is associated with a first change from the first voltage level to the second voltage level;
• applying a second excitation voltage to the electrode of the touch sensor, wherein applying the second excitation voltage to the electrode charges the capacitive node from the second voltage level to a third voltage level that is greater than the second voltage level;
• discharging the capacitive node from the third voltage level to a fourth voltage level that is less than the second voltage level;
• determining a second charge measurement, wherein the second charge measurement is associated with a second change from the third voltage level to the fourth voltage level;
• and
• determining a measured charge signal based on the first charge measurement and the second charge measurement;
• wherein the first excitation voltage and the second excitation voltage are each derived from a reference voltage.

A device, comprising:

• a touch sensor;
• and
• a processor configured to perform operations comprising:
• applying a first excitation voltage to an electrode of a touch sensor, wherein applying the first excitation voltage to the electrode charges a capacitive node associated with the electrode from a first voltage level to a second voltage level that is greater than the first voltage level;
• determining a first charge measurement, wherein the first charge measurement is associated with a first change from the first voltage level to the second voltage level;
• applying a second excitation voltage to the electrode of the touch sensor, wherein applying the second excitation voltage to the electrode charges the capacitive node from the second voltage level to a third voltage level that is greater than the second voltage level;
• discharging the capacitive node from the third voltage level to a fourth voltage level that is less than the second voltage level;
• determining a second charge measurement, wherein the second charge measurement is associated with a second change from the third voltage level to the fourth voltage level;
• and
• determining a measured charge signal based on the first charge measurement and the second charge measurement;
• wherein the first excitation voltage and the second excitation voltage are each derived from a reference voltage.