Patent ID: 7777501

Claim:
A system for measuring each of a plurality of measurable capacitances, the system comprising: at least one passive network coupled to the plurality of measurable capacitances, each of the at least one passive network comprising at least one integrating capacitance configured to accumulate charge received from the plurality of measurable capacitances; at least one charge changing circuit coupled to the at least one passive network; and a controller, the controller including a plurality of digital outputs, each of the plurality of digital outputs coupled to a measurable capacitance in the plurality of measurable capacitances, the controller configured to measure each of the plurality of measurable capacitances by, for each selected measurable capacitance in the plurality of measurable capacitances, repeatedly applying a voltage to the selected measurable capacitance using a digital output in the plurality of digital outputs, repeatedly sharing charge between the selected measurable capacitance and the at least one passive network to accumulate charge on the at least one integrating capacitance, and repeatedly changing a charge on the at least one integrating capacitance by a quantized amount of charge using the at least one charge changing circuit in response to the charge on the at least one passive network being past a threshold of a quantizer, the quantized amount of charge determined at least in part as a function of an output of the quantizer.