## 6 Conclusions  
Based on the simulation framework for the 40 nm technology node via a reliability simulator called the Eldo simulator, the effect of delay degradation on the FPGA was studied, along with aging sensor detection. The simulation results obtained from the Eldo simulator showed that the aging degradation over ten years shows a degradation trend of between 0.04 and 0.09% per year due to the NBTI degradation effect. Therefore, an aging sensor was implemented that detected seven points of aging degradation based on the phase shift delay. The results obtained from this aging sensor show that the degradation rate was 13.89% for each phase shift, which is in line with the NBTI degradation effect on the FPGA. For the optimization of the FPGA performance, the usage of the automatic clock correction scheme was vital to ensure that the output produced by the FPGA was consistently at the optimal level with a minimal delay effect. The experiment conducted on the 40 nm Virtex-6 FPGA also found that the coefficient of variation and standard deviation for the automatic clock correction scheme were 0.02% and 1.33%, respectively.  
Therefore, the effect of the delay on the FPGA was mainly caused by the NBTI degradation effect, which can be translated into a lifetime prediction table that can help system designers and industrial users to replace the FPGA chip at the appropriate time. The data obtained were supported by several FPGA companies, such as Xilinx, Altera, and Lattice Semi. Based on the obtained results, it was shown that each FPGA had a different remaining lifetime due to the percentage utilization of the CLBs. Therefore, the delay retrieved from the FPGA had a performance shrinkage of about 13.89% for each 50\({}^{\circ}\) phase shift difference. This performance shrinkage showed that the effect of the NBTI on the 40 nm Virtex-6 FPGA occurred, although the technology size continues to shrink.  
[PERSON] designed and developed the aging sensor and wrote the original/revised drafts manuscript. [PERSON] and [PERSON] revised the manuscript and conducted data analysis of the research work. [PERSON] and [PERSON] verified data and conducted the statistical analysis. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors would like to acknowledge the Faculty of Engineering at the University of Malaya and the Faculty of Electronics and Computer Engineering and Centre for Research and Innovation Management (CRIM) at the Universiti Teknikal Malaysia Melaka (UTeM) for financial support and technical contributions.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Device under Test** & **Sensor Location** & \begin{tabular}{c} **The Complexity** \\ **of the Design** \\ \end{tabular} & \begin{tabular}{c} **Automatic Clock** \\ **Correction** \\ **Scheme** \\ \end{tabular} & \begin{tabular}{c} **Types of Frequency** \\ **Detection** \\ \end{tabular} & **Reference** \\ \hline Spartan-6 45 nm & Local sensor & \begin{tabular}{c} Complicated \\ design \\ \end{tabular} & Not available & The detection process only & [26] \\ Virtex-6 40 nm & Local sensor & Simple & Not available & \begin{tabular}{c} agents without a specific \\ detection range \\ \end{tabular} & [27] \\ Spartan 3 AN 90 nm & Local sensor & \begin{tabular}{c} Complicated \\ design \\ \end{tabular} & Not available & \
\begin{tabular}{c} detection range \\ \end{tabular} & [31] \\ Virtex-6 40 nm & Local sensor & Simple & Automatically &
\begin{tabular}{c} Multiple points of detection \\ that identified the specific \\ range of the aging condition \\ \end{tabular} & This \\ \hline \hline \end{tabular}
\end{table}
Table 6: Comparison of aging sensor design with automated clock correction scheme.