*2.2. Theoretical Backgound*

The entire research methodology employed throughout this paper can be summarized as shown in Figure 2. First, the temperature sensitivity of all LEDs has to be determined and then their thermal responses to the power step thermal excitations have to be recorded. Then, according to the principles of the network identification by deconvolution (NID) method, these responses have to be numerically di fferentiated so as to obtain the responses to the Dirac delta function and then the deconvolution operation produces the thermal time constant spectra [28], which after segmentation, according to the later described procedure, yield initial compact thermal model element values. Finally, these values are further optimized so as to minimize the simulation errors with respect to the measurements [29].

**Figure 2.** The flowchart illustrating the research methodology employed throughout this paper.
