Patent ID: 6946987

Claim:
A common operational amplifier for a pipeline circuit, the pipeline circuit comprising a plurality of stage circuits, and the common operational amplifier being used by the stage circuits by turns according to a predetermined timing, the common operational amplifier comprising: an operational amplifier circuit, for receiving and amplifying a first signal set, and outputting a second signal set correspondingly; a multiplexer circuit, comprising a plurality of first input terminal sets and an first output terminal set, for selecting one of the first input terminal sets by turns according to the predetermined timing, and the selected one of the first input terminal set is connected to the first output terminal set, wherein each of first the input terminal sets is respectively connected to each of the stage circuits correspondingly to receive a third signal set of each of the stage circuits, and the first output terminal set is connected to the operational amplifier circuit to output the first signal set; and a demultiplexer circuit, comprising a second input terminal set and a plurality of second output terminal set, for selecting one of the second output terminal sets by turns according to the predetermined timing, and the second input terminal set is connected to the selected one of the second output terminal set, wherein the second input terminal set is connected to the operational amplifier circuit to receive the second signal set, and each of the second output terminal sets respectively connected to each of the stage circuits correspondingly to output a plurality of 4th signal set.