Operational amplifier circuit and band gap reference source

The invention provides an operational amplifier circuit and a band gap reference source. The operational amplifier circuit comprises a differential amplification unit, a load unit, a tail current source pipe, a detection unit and a mirror image pipe, wherein the differential amplification unit is suitable for differential amplification of first voltage and second voltage, and third voltage is output; the load unit receives fourth voltage and is suitable for providing loads for the differential amplification unit; the tail current source pipe receives fifth voltage and is suitable for generating bias current provided for the differential amplification unit under the control of bias voltage received by a control terminal; the detection unit is suitable for detecting output voltage of the tail current source pipe and outputting first control voltage, wherein the variation trend of the first control voltage and the variation trend of the output voltage of the tail current source pipe are consistent; the input end