Patent ID: 7893932

Claim:
An electronic circuit having transistors disposed on a substrate, each transistor including an active layer made of thin-film polysilicon, the electronic circuit comprising: a sensor that converts a measured quantity into a current value; a current-voltage conversion circuit that converts the current value into a voltage; and a voltage detection circuit that detects the voltage converted by the current-voltage conversion circuit and outputs a predetermined signal, wherein the current-voltage conversion circuit includes a range-switching circuit that switches from a first current-voltage conversion range to a second current-voltage conversion range, wherein the current-voltage conversion circuit has field-effect transistors each including an active layer made of thin-film polysilicon disposed on the substrate and includes a first transistor and a second transistor connected in parallel, and a control circuit that is connected to the second transistor and controls a current flowing into the second transistor; and wherein the second transistor and the control circuit constitute the range-switching circuit, and by controlling the current flowing into the second transistor by a range-switching signal, the first current-voltage conversion range of the current-voltage conversion circuit is switched to a second current-voltage conversion range.