| The semiconductor has played more and more important role in theinformation society as the core of the semiconductor optoelectronics. And withits superior characteristic, it has penetrated into the area which the other laserscannot set foot in .For the above facts, it has drawn wide attention, and at thesame time, a higher quality semiconductor laser is needed. Semiconductorlaser diode, as a core device of optical fiber communication, has the characterof high efficiency, small size, low weight, high reliability, direct modulationand high integrated ability with other semiconductor devices. The outputpower will periodically or stochastically fluctuate when the semiconductorlaser diode is operating. The majority of the semiconductor laser diode in ourcountry is more fluctuant than abroad. It is necessary that the output power ofthe semiconductor laser diode has higher stability while using it for delicatemeasure. Otherwise, the variety of light power will affect measure accuracy.So it is very important to design laser diode drive power supply, especially todesign high-power laser diode drive power.There is a laser diode drive power supply called JD2500 in our lab atpresent. This paper introduces the design of constant power drive module andthe improvement of big current. The laser diode drive power supply outputcurrent is 18 A by improving.Negative feedback can improve enlarged circuit performance, such asimprove stability, decrease nonlinear distortion, extend frequency band.Thereby the whole design idea is to use the principle of negative feedback tostabilize output current in constant current drive module. In order to obtain thelowest current error and the highest current stability, high-stability datumvoltage supply, high-quality operational amplifier, voltage-control currentsource IRF640 and delicate sampling resistance are used in the circuit.Sampling resistance can change the current into voltage while controlling. Thevoltage signal is fed back via resistance feedback circuit. The feedback singleis compared with input current initialization. The difference is enlarged tocontrol drive circuit output current. Sampling and drive are repetition. In orderto extend constant current drive power supply output current range, we can usemore IRF640s parallel connection in the circuit. Several IRF640s parallelconnection can achieve big current and each power MOSFET drain current isthe same in theory. But each power MOSFET drain current is different inactually. The reason is that manufacture art effects on power MOSFET. If thecurrent too big ,the power MOSFET which has bigger drain current dissipationpower will increase. And the dissipation power change into heat energy tomake power MOSFET temperature gets high. In order to restrict itstemperature, we should insure that its dissipation power is low its rate power.This paper analyses several power MOSFET parallel connection drain currentequalization. That is to say that big current of constant current drive is solved.In constant power drive module, we can't use practical semiconductorlaser diode module with PD as load. We use light coupling apparatus insteadof semiconductor and photoelectric diode in experiment. PD converts thechange of output light power of laser diode into the change of diode current,and the change of current is fed back to voltage-current converser whichadjusts output current of driver to compensate the laser diode.This work mentioned in the paper has positive significance to the wideapplication of semiconductor laser diode, which solves key questions in theapplication of semiconductor laser diode. The practical application indicatesthat the driver has the following advantages: strong anti-interference ability,high stability and no damages to laser diodes. |
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