Electronic circuit, module, and system

A convenient electronic circuit in which a switch is able to be switched through electric power obtained using weak radio waves is provided. An electronic circuit includes a switch which is connected between a power supply configured to output direct current (DC) electric power and a load driven through DC electric power supplied from the power supply and which switches a connection state between the power supply and the load from a non-conduction state to a conduction state; a power conversion circuit which includes a power input terminal to which electric power obtained through radio waves received by an antenna is input and a DC power output terminal configured to output DC electric power and which converts electric power input to the power input terminal into DC electric power and outputs the converted DC electric power from the DC power output terminal; and a control circuit configured to control a connection state of the switch to be in a conduction state when the power conversion circuit outputs DC electric power. The power conversion circuit includes at least a first capacitor, a first diode, a second capacitor, and a second diode.