Accurate Controllable 325W Laser Diode Driver for Optical Inter-Satellite Links

A 325W radiation hard, controlled current source is developed and qualified for use in optical inter-satellite communication links. The nature of the application requires accurate control of the current setpoint from 0.5A to 10A as well as adjustable maximum output voltage from 3V to 32.5V to ensure protection of the laser diodes. The wide range of operating conditions pose a challenge to ensure proper gain and phase margin while meeting requirements for transient response to load step and setpoint changes. The control scheme is an augmentation of peak current mode control to include separate setpoints for the voltage control and average current mode control which has proven effective in meeting the application requirements. This paper presents the converter topology, control scheme design and methods for radiation hardening of the circuits. The achieved performance of the current source is demonstrated by measurements on the manufactured hardware.