A circuit includes a current mirror circuit (CM circuit) including first and second transistors, a third transistor whose drain is electrically connected to a drain of the second transistor, a switch controlling the current output from the circuit, and first and second memory circuits. A reference current of the CM circuit is input to a drain of the first transistor; a current that is a copy of the reference current is output from the drain of the second transistor. When a current is output from the circuit, the reference current is not input to the CM circuit. A drain current corresponding to a voltage stored in the first memory circuit flows through the second transistor; a drain current corresponding to a voltage stored in the second memory circuit flows through the third transistor. The difference between the two drain currents corresponds to the output current of the circuit.