Design of a Digital Control Laser Driving Source Based on Dual Feedback Theory

In the first, show the important factors that influence the working condition and service life of the laser diode. Then, aim at the stability and reliability of the current, brought forward a dual feedback constant current driving plan based on deeply negative feedback theory and PID algorithm. Utilizing deeply negative feedback theory to strengthen the stability of system, decrease nonlinear distortion, expand the bandwidth and enhance the load capacity of the system. Analyze the reason of bias current in the past laser driving system´s design, and posed an improvement. In ripple reject circuit, through the capacitance change using MOSFET, utilize a small capacitor to bring in the filtering effect of a big capacitor. Design and realize a power supply filter network which has a very low ripple coefficient and soft turn-on/off circuit, they secure the working of the laser.