| 摘要 |
PURPOSE:To increase the maximum operating frequency of a light emitting diode by providing means for controlling the charging/discharging of an equivalent capacity of the diode at the anode or cathode side of the diode. CONSTITUTION:A coil 26 is connected as the collector of a transistor (TR) 22 for supplying a prebias current, and connected to the collector of a TR 2 for driving an LED as a whole bias current supplying circuit 25, i.e., the cathode of the LED1. The emitter of the TR 22 is grounded through a prebias current limiting resistor (R) 24. R21 for applying the bias of the base and a diode 23 for a base bias constant voltage are connected to the base of the TR 22 so that the base voltage of the TR 22 becomes constant and the TR 22 always becomes ON. Thus, a constant bias current always flows to the LED 1 to shorten the rising and falling times of the TR 2, thereby enhancing the maximum operating frequency of the LED. |
