**7. Conclusions**

The NTC design paradigm, being a stronger direction towards energy efficiency, is plagued by timing errors for DNN applications. In this paper, we illustrate the unique challenges coming from the DNN workload and attributes of the occurrence and impact of timing errors. We discover that NTC DNN accelerators are challenged by landslide increases in the rate timing errors and the inherent algorithmic tolerance of DNNs to timing errors is quickly surpassed with a sharp decline in the inference accuracy. We explore the data–delay relationship with the practical DNN datasets to uncover an opportunity of providing bulk timing error resilience through prediction of a small group of high delay input sequences. We explore the timing disparities in the multiplier and accumulator to propose opportunities for providing an elegant timing error correction without performance loss. We correlate the hardware utilization pattern to outshine the broad control strategies for timing error resilience techniques. The application of NTC in the domain of DNN accelerators is a relatively newer domain and this article serves to present concrete possible directions towards timing error resilience, which remains to be a big hurdle for NTC systems. Energy efficient AI evolution is the need of the hour and further research with promising domains, such as NTC is required.

**Author Contributions:** Conceptualization, P.P. and N.D.G.; methodology, P.P., N.D.G., P.B. and T.S.; software, P.B., P.P., N.D.G. and T.S.; validation, P.P. and N.D.G.; formal analysis, P.P. and N.D.G.; investigation, P.P., N.D.G., P.B., T.S. and M.C.P.; resources, P.P., N.D.G., P.B., T.S., K.C. and S.R.; data curation, P.P.; writing—original draft preparation, P.P. and

N.D.G.; writing—review and editing, P.P., N.D.G., K.C. and S.R.; visualization, P.P. and N.D.G.; supervision, K.C. and S.R.; project administration, P.P.; funding acquisition, K.C. and S.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported in part by National Science Foundation under gran<sup>t</sup> numbers CAREER-1253024 and CNS-1421022.

**Conflicts of Interest:** The authors declare no conflict of interest.
