An operational amplifier is disclosed. The operational amplifier comprises an input stage and a loading stage. The input stage receives a differential input signal pair corresponding to a first frequency band. The loading stage is coupled to the input stage. The loading stage outputs an amplified differential output at output nodes. The loading stage comprises a flicker noise source and a modulating device. The modulating device is coupled to the flicker noise source. The modulating device modulates flicker noises into a second frequency band. The modulating device is not within a signal path.