| 摘要 |
<p>PURPOSE:To ensure response to the deterioration, etc. of a luminous element used for an optical communication device by a method wherein a standard drive current setting circuit and a reference voltage value setting circuit are mounted to a semiconductor luminous monitoring circuit, both circuits are interlocked and a reference voltage value is automatically brought to a proper value with the variation of a standard drive current value. CONSTITUTION:The first amplifier 23, the second amplifier 26 with resistors 24, 25 deciding gains and a transistor 30 for driving a laser are connected between the semiconductor laser 20 and a light detector 21 for detecting the output of the laser 20. An emitter of the trasistor 30 is grounded through a resistor 31 while being branched and being connected to a comparator 32, and a series circuit consisting of a constant-voltage source 28 and the third amplifier 29 is installed between the second amplifier 26 and the comparator 32. In such constitution, the output of the laser 20 is detected by means of the detector 21, the signals are negatively fed back to the transistor 30 through the amplifier 26, the circuit is stabilized while set voltage VB is applied to the amplifier 29 through the constant-voltage source 28, and the output is used for a reference value VS of the comparator 32.</p> |
