Patent ID: 6914387

Claim:
A driving circuit for a light emitting element, said driving circuit supplying a bias current and a modulation signal to said light emitting element for voltage driving, said driving circuit comprising: a boosting circuit that has an output terminal, said boosting circuit boosting a power supply voltage applied thereto and outputting a boosted power supply voltage from said output terminal; a digital potentiometer connected between said output terminal of said boosting circuit and an anode terminal of said light emitting element; a capacitive element connected to said anode terminal of said light emitting element to supply said modulation signal to said light emitting element; a light receiving element for outputting a current corresponding to an optical output emitted from said light emitting element; and a control circuit for varying a resistance of said digital potentiometer based on said current output from said light receiving element; wherein said control circuit includes an A/D converter that outputs a digital signal and controls said digital potentiometer based on said digital signal output from said A/D converter to vary said resistance.