Patent ID: 9007074
Filing Date: 2015-04-14
Classification: G01D,G01R

Abstract:
1. A circuit for sensing a differential capacitance, comprising: a first sensing terminal and a second sensing terminal connected to two terminals of the differential capacitance; a switching circuit connected to the first and second sensing terminals, for being switched to cause the two terminals of the differential capacitance either to be connected to one of a high-voltage source and a low-voltage source for charge sampling or to perform charge transfer; a charge-storing circuit coupled to the switching circuit for storing charges transferred by the differential capacitance in response to a switching of the switching circuit, the charge-storing circuit comprising: a first storing circuit including a plurality of first storing capacitors, for sequentially storing charges sampled at one of the terminals of the differential capacitance in different transfer rounds into a different one of the plurality of first storing capacitors, so as to generate a first output voltage; and a second storing circuit including a plurality of second storing capacitors, for sequentially storing charges sampled at the other terminal of the differential capacitance in the different transfer rounds into a different one of the plurality of second storing capacitors, so as to generate a second output voltage; and an amplifier stage for generating a sensing value according to a difference between the first and second output voltages; wherein the plurality of first storing capacitors are coupled to the two terminals of the differential capacitance by the switching circuit; and wherein the plurality of second storing capacitors are coupled to the two terminals of the differential capacitance by the switching circuit.