System and method for area-efficient monitoring of clock signals

A clock monitoring system, comprising:

• a first input configured to receive a monitored clock signal;
• a window duration memory unit configured to store a value determining an evaluation window duration;
• a second input configured to receive a reference clock signal;
• a toggle signal generator configured to use the evaluation window duration to generate a toggle signal using the reference clock signal, wherein the toggle signal toggles to a first value which is maintained to an end of the evaluation window duration defined by a plurality of reference clock cycles of the reference clock signal and toggles to a second value which is maintained during a next evaluation window,
• a clock signal detector coupled to the toggle signal generator and configured to receive the monitored clock signal, wherein the clock signal detector is configured to generate an output signal equal to the toggle signal when the monitored clock signal is present at an input to the clock signal detector wherein the output signal is generated in response to one edge of the monitored signal being in the evaluation window duration;
• and
• a loss of clock detector coupled to the toggle signal generator and the clock signal detector, wherein the loss of clock detector is configured to:
• compare the output signal of the clock signal detector to the toggle signal;
• and
• when the output signal of the clock signal detector is not equal to toggle signal, generate an output signal indicative of a loss of clock signal condition.

A method, comprising:

• receiving a reference clock signal;
• generating a toggle signal using the reference clock signal, wherein the toggle signal toggles to a first value which is maintained to an end of an evaluation window duration defined by a plurality of reference clock cycles of the reference clock signal and toggles to a second value which is maintained during a next evaluation window;
• generating a clock detector output signal equal to the toggle signal when a monitored clock signal is received, wherein the clock detector output signal is generated in response to one edge of the monitored signal being in the evaluation window duration;
• comparing the clock detector output signal to the toggle signal;
• and
• when the clock detector output signal is not equal to the toggle signal, generating an output signal indicative of a loss of clock signal condition.