Electronic circuit, module, and system

A convenient electronic circuit in which a switch can be switched through electric power obtained using weak radio waves is provided. An electronic circuit includes: a power supply configured to output direct current (DC) electric power; a switch which switches a connection state between the power supply and a load; a first power conversion circuit which converts electric power obtained using first radio waves received by a first antenna capable of receiving the first radio waves in a first direction into DC electric power and which outputs the converted DC electric power from a first DC power output terminal; a second power conversion circuit which converts electric power obtained using second radio waves received by a second antenna capable of receiving the second radio waves in a second direction different from the first direction into DC electric power and outputs the converted DC electric power from a second DC power output terminal; and a control circuit which controls a connection state of the switch such that it is in a conduction state when the first power conversion circuit outputs DC electric power due to the reception of the first radio waves by the first antenna and controls the connection state of the switch such that it is in a non-conduction state when the second power conversion circuit outputs DC electric power due to the reception of the second radio waves by the second antenna.