Direct Continuous-Time Model Identification of High-Powered Light-Emitting Diodes from Rapidly Sampled Thermal Step Response Data

Abstract Transient temperature response measurements of semiconductor devices such as high-powered Light-Emitting-Diodes (LEDs) can be used to detect possible thermal defects. The thermal transient responses of these LEDs appear to be stiff which can be represented by a model with both fast and slow dynamics. It is shown how direct continuous-time model estimation methods, such as the Simplified Refined Instrumental Variable method for Continuous systems (SRIVC), can directly identify with high accuracy a model with both small and large time-constants that can reproduce the thermal effects of the LEDs while conventional discrete-time model identification fails in this stiff response situation.