| 摘要 |
PURPOSE:To obtain sharp rising characteristic with small sag without optical output by providing an amplitude limiter before the drive signal input unit of a current switching type light emitting element drive circuit, and setting the amplitude of a signal input to a suitable value in response to the optical output of the element. CONSTITUTION:An amplitude limiter 13 suppresses a modulation signal of amplitude 2Vin to be input to a positive phase signal input terminal 14 and a reverse phase signal input terminal 15 at an arbitrary ratio, and outputs an output signal having the same polarity as that of the modulation signal to a first transistor 1 and a signal having reverse polarity to a second transistor 2. The output amplitude of the limiter 13 is set to an arbitrary value at an output amplitude set terminal 16. The input amplitudes of the first and second transistors 1, 2 are set to suitable values in response to the optical output of a light emitting element 5, thereby obtaining a suitable sag at the rise of the driving current of the element 5 and attaining an optical output waveform having a sharp rising and a small sag. |
