| 摘要 |
PURPOSE:To give an approximately complete compensation to the distortion and frequency characteristics, by integrating the driving current of a light emitting element in response to the thermal time constant of the light emitting element and controlling the level of the driving input of the light emitting element with the integral output. CONSTITUTION:The output of an analog signal source 1 is supplied to a variable gain amplifier 3, and the output of the amplifier 3 is supplied to a light emitting element 5 via a driving circuit 4. At the same time, the output of the source 1 is integrated by an integrator 2 and the integral output is supplied to the amplifier 3. The integrator 2 integrates the output of the source 1 in response to the thermal time constant of the element 5. The voltage based on the integration is supplied to the amplifier 3, and therefore the gain of the amplifier 3 varies in accordance with the integral value. Thus the level of the input signal of the element 5 varies in accordance with the thermal time constant of the element 5. As a result, the optical output variation due to a change of the optical output- injection current characteristics caused by the self-generated heat of the element 5 is eliminated. |
