Abstract: High altitude electromagnetic pulse (HEMP) can produce electromagnetic pulse effects on electronic devices or systems that cannot be ignored. In this paper, a high-speed comparator and a clock driver are selected, and the electromagnetic sensitivity of the power modules of these two devices is studied by the experimental method of pulse current injection (PCI). The test results show that the rising edge of the double exponential pulse current is the main cause of the output glitch of the high-speed comparator and clock driver, and the amplitude of the disturbance is affected by the amplitude of the injected pulse current. The electromagnetic sensitivity of the power module of the high-speed comparator is different at different output level. Different operating frequencies of high-speed comparators and clock drivers will show different electromagnetic sensitivity. The results have certain guiding significance for electromagnetic sensitivity analysis and hardening of electronic devices or systems.