A Loss of Reference Clock Detect Circuit

Loss of reference clock may harm the functionality of system on chips (SoCs) permanently or intermittently. In this paper, we propose a novel circuit based on an XOR phase detector and a simple charge pump to monitor the input reference clock continuously. This circuit can provide a signal to indicate the loss of reference clock. SPICE simulation results confirm that the proposed reference clock detect circuit can monitor the input reference clock and provide a correct indication signal.