Low-power frequency monitoring circuit for clock failure detection

In security and safety-critical applications, detecting a clock failure may prevent or at least mitigate the consequences of system faults by letting the system enter a backup state when such an alarm is triggered. In this paper, we propose an RC-based frequency monitoring circuit suitable for embedded clock failure detection, focusing on low-power consumption and robustness against environmental and manufacturing variations. The monitor was implemented in GlobalFoundries 22FDX technology and designed to trigger for an input clock frequency lower than a trimmable threshold. When considering a test case of a fail-safe LCD controller, the trimmed frequency threshold of 22 kHz was found to vary less than 1% over PVT corners while consuming only 150 nW.