High speed driving circuit for semiconductor light emitting element

Abstract

Abstract PURPOSE:To generate an optical pulse at a high speed by connecting the emitters of conductive transistors (TRs) having reversed conductivity each other in common, positive and negative power sources to respective collectors and capacitor to the positive power source. CONSTITUTION:The collectors of an n-p-n TRQ1 and a p-n-p TRQ2 are connected to a positive power source +V and a negative power source -V respectively, the emitters of both the TRs are connected in common and a semiconductor light emitting diode LD is connected between the common connection point and the earth. The collector of the TRQ1 is earthed through a capacitor for accelurating at the time of rising. When the bases of the TRs Q1, Q2 are connected in common and a control pulse P is applied to the common connection point, the TRQ1 is turned on, current I1 flow from the power source +V into the TRQ1 and current IC due to the charge of the capacitor C also flows suddenly into the TRQ1. Consequently the rising time of an optical pulse OP of the element LD is reduced. When the generation of pulses P is turned off, the TRQ1 is turned off, the emitter of the TRQ2 is biased in the forwrd direction by the electric charge accumulated in the junction capacitor of the LD, so that the TRQ2 is turned on and the pulse P falls quickly.

Inventors

• 👤 Akitake Sawano
• 👤 澤野　驍武

Bibliographic Details