PURPOSE: To make the pulse width of an output pulse signal outputted from a comparator stable against a temperature fluctuation by making a relative level difference between the output voltage of an amplifier fed to the comparator and a comparison voltage outputted from a level shift circuit nearly constant against a temperature change.
CONSTITUTION: With a prescribed minute signal inputted to a photodetector 1, an output voltage appears at the output of an amplifier 2. When ambient temperature rises, an output voltage EO2 is lowered. On the other hand, a current I0 flowing to the collector of a constant current source transistor(TR) Q1 is increased. As a result, a change in a voltage outputted from a level shift circuit 5 is coincident with a temperature change and a level difference between both is nearly constant against the temperature fluctuation. Thus, the pulse width of an output pulse signal outputted from the output terminal 3 out of the comparator 3 is made stable against the temperature fluctuation.
ISHIKAWA FUMIO
AOKI TAKAYUKI
