Laser diode driving circuit

Abstract

Abstract PURPOSE:To improve control precision by using a switching and a bias electric currents as driving current and performing light output control by the bias current. CONSTITUTION:Current sources 10A and 10B are current sources for the switching current and bias current. The output of a laser diode (LD) 3 is detected by a photodiode 4 and supplied through an amplifier 14 to a comparator 13, where it is compared with a reference voltage. Then, the output of the comparator 13 is supplied to a U/D counter 12, which counts up or down. Its counted value is converted by a D/A converter 11 into an analog value, which controls the capacity of the current source 10B to vary the bias current, performing constant-output control over the LD 3. Thus, the object under the constant-output control is only the bias current and reduced in range, so the control precision is improved.

Inventors

• 👤 Jinichi Hongo
• 👤 本郷　仁一
• 👤 Shoichi Ito
• 👤 伊東　正一

Bibliographic Details