COMMUNICATION SYSTEM

A communication circuit generates a clock signal that is a digital signal corresponding to a serial clock, and a data signal that is a digital signal corresponding to serial data to be sent. A modulation circuit generates a first modulated signal obtained by digital modulating a first carrier wave having a first frequency with the clock signal and second modulated signal obtained by modulating the second carrier wave having a second frequency different than the first frequency with the data signal, and applies the first modulated signal and the second modulated signal between a first conductor and a second conductor. A demodulation circuit includes a buffer amplifier that has high input impedance, demodulates the first modulated signal and the second modulated signal, and generates the clock signal and the data signal. The communication circuit acquires serial data on the basis of the clock signal and the data signal.