On-chip glitch-free backup clock changer with noise canceller and edge detector for safety MCU clock system

The embedded microcontroller is operated by the logic gates synchronized on the clock pulses. Severe electrical situations such as high voltage/frequency surge may cause malfunctioning of the clock source. Due to the broken clock, the clockless status of the system may enter into an abnormal state in driving several dangerous output. The glitch-clock pulse by abnormal clock generation causes the inversion of flip-flops status. In this paper, we propose an on-chip clock controller architecture to detect automatically clock failure and to switch the safe backup clock. The implemented edge detector (ED) unit identifies the abnormal low-frequency status of the clock source. The noise canceller (NC) using delay chain circuit of the clock pulse can detect the glitch status of the system clock. The simulation results show that the clock source damaged by external disturbance is successfully restored into safe clock status by the proposed on-chip glitch-free backup clock changer.