| 摘要 |
PURPOSE:To obtain high speed switching characteristics with respect to fluctuation in ambient temperature by a method wherein a current source of two pairs of transistors are constituted of compensation circuits with which the output of a light emitting device is almost constant with respect to fluctuation in temperature. CONSTITUTION:A first driving current source K1 of a first pair of transistors Q1, Q2 consists of a transistor Q9 with an emitter resistor R9 connected and a base bias compensation circuit T9 connected to a base terminal. Bias voltage of the compensation circuit 9 changes in a positive direction with respect to fluctuation in ambient temperature and the circuit 9 compensates fluctuation in light emitting characteristics in a negative direction with respect to temperature of a light emitting device so that constant output can be obtained. On the other hand, a base bias compensation circuit T10 of a second driving current source K2 of a second pair of transistors A3, A4 is formed so that current ratio of the first current source K1 and the second one is almost constant. |
