Charge balancing converter using a passive integrator circuit

摘要

A method, apparatus, and system are described to perform, by a capacitance-sensing circuit, capacitance sensing of an electrode of a capacitive sense array of electrodes. Performing the capacitance sensing includes integrating, on a passive integrator circuit, charge from a sensed capacitance of the electrode of the capacitive sense array. The passive integrator circuit integrates the charge on a self-capacitance of the electrode as part of the integrating. The capacitance-sensing circuit converts the charge from the sensed capacitance of the electrode into a digital value representing the sensed capacitance of the electrode.

主权项

1. A method comprising:
at a capacitance-sensing circuit electrically coupled to a capacitive sense array of electrodes and including a current generator:
performing capacitance sensing of an electrode of the capacitive sense array of electrodes, including:
configuring a passive integrator circuit to include a first capacitor associated with a self-capacitance of the electrode, wherein the first capacitor is formed between the electrode and a ground;balancing by the current generator charge integrated on the passive integrator circuit; andsensing the charge integrated on the passive integrator circuit, wherein the sensed charge is indicative of a sensed capacitance associated with at least one of the self-capacitance and a mutual capacitance of the electrode; andconverting the sensed charge indicative of the sensed capacitance of the electrode into a digital value, wherein the digital value corresponds to a length of time for balancing the charge integrated on the passive integrator circuit and associated with the sensed capacitance of the electrode.