In differential amplifier circuitry formed on a semiconductor substrate, first and second transistors constitute a differential pair of the differential amplifier circuitry. First and second pads are connected with emitters of the first and second transistors, respectively. The first and second pads are connected with first and second external ground terminals via first and second rewiring layers to be grounded, respectively. The first and second rewiring layers are preferably connected with each other. Further, bases of the first and second transistors are connected with first and second bias circuits via first and second resistors, respectively.
