Patent ID: 8519792

Claim:
A differential voltage sensing system comprising: a first amplifying circuit; a first variable resistor having an input terminal connected to a first node, an output terminal connected to a first input terminal of the first amplifying circuit, and a control terminal; a second variable resistor having an input terminal connected to a second node, an output terminal connected to a second input terminal of the first amplifying circuit, and a control terminal; a signal capture unit connected to an output terminal of the first amplifying circuit; and a logic control unit connected to the signal capture unit and to the control terminal of the first variable resistor and to the control terminal of the second variable resistor; wherein impedances of the first and second variable resistors are adjusted dynamically according to output signals of the logic control unit so as to achieve input impedance matching, and wherein total impedances in a serial path between the first input terminal of the first amplifying circuit and a first corresponding electrode and between the second input terminal of the first amplifying circuit and a second corresponding electrode are equalized.