Laser diode driver on a programmable system on a chip

Abstract

A comprehensive solution of a laser diode (LD) driver with temperature control using a programmable system on a chip is proposed as an alternative to dedicated devices. A digital proportional integral differential controller is used for regulating the LD temperature. The light–current characteristics and frequency response of the LD are measured using an external photodiode and interrogated by an integrated transimpedance amplifier. The 0.084% stability, 2 kHz bandwidth, and 0.11% full scale current error are demonstrated. The LD overshoot protection is digitally implemented, providing a soft start. While the circuit is initially optimized for a 3 W infrared LD, instructions are provided for fine-tuning the design according to specific LD requirements.