The disclosed apparatus includes a plurality of differential transmitters, and a power supply circuit that supplies a power supply voltage to each of the plurality of differential transmitters. The power supply circuit includes a common circuit unit that defines the power supply voltage supplied to the plurality of differential transmitters, and a plurality of individual circuit units provided in association with the plurality of differential transmitters and each connected to the common circuit unit. Each of the plurality of individual circuit units has an output node that outputs the power supply voltage defined by the common circuit unit to a corresponding differential transmitter of the plurality of differential transmitters, and respective output nodes of the plurality of individual circuit units are connected to each other.