Patent ID: 8040180

Claim:
An operational amplifier capable of compensating offset voltage comprising: an input stage circuit comprising a positive input end, a negative input end, a first current output end, and a second current output end, for outputting currents from the first current output end and the second current output end according to voltage received from the positive input end and the negative input end; an output stage circuit coupled to the first current output end and the second current output end, for outputting voltage according to the currents outputted from the first current output end and the second current output end; and a trimming device, comprising: a first current-mode digital to analog converter (DAC) coupled to the first current output end, for outputting or receiving current through the first current output end according to a control signal; a second current-mode DAC coupled to the second current output end, for outputting or receiving current through the second current output end according to the control signal; and a control unit coupled to the first current-mode DAC and the second current-mode DAC, for outputting the control signal according to a current difference between the first current output end and the second output end, for controlling a current amount outputted or received by the first current-mode DAC through the first current output end, and a current amount outputted or received by the second current-mode DAC through the second current output end.