DC offset cancellation circuit

A DC offset cancellation circuit receiving a first sensing current from a first sensing unit and a second sensing current from a second sensing unit, the DC offset cancellation circuit comprising:

• a superposing unit for generating a first DC current and a second DC current, wherein after the first DC current and the first sensing current are superposed with each other by the superposing unit, a first superposed current is generated, wherein after the second DC current and the second sensing current are superposed with each other by the superposing unit, a second superposed current is generated;
• a first current-to-voltage converter for converting the first superposed current into a first voltage signal;
• a second current-to-voltage converter for converting the second superposed current into a second voltage signal;
• a differential amplifier having a first input end receiving the first voltage signal, a second input end receiving the second voltage signal, and an output end generating an output signal;
• a processing unit for receiving the output signal and processing the output signal into a DC value and a control signal, wherein a gain value of the differential amplifier is correspondingly adjusted according to the control signal;
• and
• a current digital-to-analog converter for converting the DC value into a DC current signal and issuing the DC current signal to the superposing unit,
• wherein the superposing unit generates the first DC current and the second DC current according to the DC current signal, so that the first superposed current and the second superposed current have the same DC offset.