| 摘要 |
<p>PURPOSE:To surely drive an optical semiconductor element at a high speed by biasing luminescing means in the forward direction according to the change in differential amplification circuit output using biasing means. CONSTITUTION:A change in a control input signal Vin, for example, from high level to low, turns on a switching transistor 4 and off another switching transistor 5. Consequently, a light emitting diode 1 is turned off. When light is off, diodes 11 and 12, a resistance 13 and a current source 14 are connected in parallel with the light emitting diode 1, and thus the output impedance of the drive circuit input, can be set low. Even if a driving signal having a different OFF interval is therefore, the forward voltage of the light emitting diode 1 just before light emission is same as a pre-bias voltage VF1, the delay and rise times of light being unchanged. This enables surely driving an optical semiconductor element at a high speed.</p> |
