A Mathematical Model of D-DMTD Glitch Signal and Performance Evaluation of Its Deglitchers Using Monte Carlo Simulation

Dual Mixer Time Difference (DMTD) is a key function measuring precise time difference between clocks in precise time synchronization and generation of standard time and frequency. Digital-DMTD is composed of digital circuits and has attracted attention as a low-cost, small, picosecond-precise measurement device, as used in the White RabbitPTP. D-DMTD has a deglitcher function that reduces timing glitches caused by clock jitter. The deglitching algorithm is one of the factors determining the precision and accuracy of D-DMTD. The performance of deglitching has been studied by comparing several algorithms through experiments. However, the relationship between the deglitching algorithm and clock jitter has not been analytically investigated from a mathematical point of view as far as we know. In this paper, we propose a glitch occurrence probabilistic model that enables us to investigate the deglitch performance analytically. We verify the effectiveness of the proposed model using the results of D-DMTD implemented on a real FPGA. Also, we evaluate the performance based on our proposed model using typical deglitching algorithms. From these results, it is shown to be a useful model that can explain the performance of the deglitch function. This model and the results will be useful and helpful for developers or designers of time synchronization systems.