Patent attributes
A photodetector continuously measure quantity of light ranging from high intensity to low intensity at high speed. The photodetector comprises an operational amplifier, a photodiode connected to an inverting terminal of the operational amplifier for outputting a signal corresponding to quantity of light to be detected, a plurality of feedback resistors differentiated in each resistance value, an analog switch for selectively connecting input terminals thereof to which one ends of the feedback resistors are connected to an output terminal of the operational amplifier except the feedback resistor having the maximum resistance value, or connecting the input terminal thereof which is rendered in a non-connection state to the output terminal of the operational amplifier instead of the feedback resistor having the maximum resistance value, wherein the feedback resistor having the maximum resistance value is connected to the output terminal of the operational amplifier at its one end and to the inverting input terminal of the operational amplifier at its other end, and wherein the other ends of the other feedback resistors are connected to the inverting input terminal of the operational amplifier.
