Patent ID: 8258864

Claim:
An offset-canceling amplifier comprising: a first differential transistor having a gate receiving a true input during an amplifying phase; a second differential transistor having a gate receiving a complement input during the amplifying phase; a first current sink transistor that sinks current from the first differential transistor; a second current sink transistor that sinks current from the second differential transistor; a first output between the first differential transistor and the first current sink transistor; a second output between the second differential transistor and the second current sink transistor; a first offset capacitor for storing a first offset charge; a second offset capacitor for storing a second offset charge; a first feedback transistor having a gate controlled by the first offset capacitor, and driving a first offsetting current to the first output in response to the first offset charge stored on the first offset capacitor; a second feedback transistor having a gate controlled by the second offset capacitor, and driving a second offsetting current to the second output in response to the second offset charge stored on the second offset capacitor; a first feedback switch for isolating the first offset capacitor from a first feedback node during the amplifying phase; a second feedback switch for isolating the second offset capacitor from a second feedback node during the amplifying phase; a first feedback resistor coupled between the first output and the first feedback node; and a second feedback resistor coupled between the second output and the second feedback node, whereby the first and second offset charge cancel differential offsets in the offset-canceling amplifier.