Phase locked loop using adaptive filter tuning for radiation hardening

A method for controlling a phase-locked loop, the method comprising:

• receiving an input signal;
• generating, with a phase error detector of the phase-locked loop, an error signal reflecting a difference between a phase of the input signal and a phase of a feedback signal of the phase-locked loop;
• detecting, with an event detector of the phase-locked loop, a loss of lock condition based at least on the phase error signal;
• filtering, with a loop filter of the phase-locked loop, the phase error signal to generate a filtered control signal based at least on a first set of filter parameter values, and in response to the loss of lock condition filter the phase error signal to generate the filtered control signal based at least on a second set of filter parameter values different from the first set of filter parameter values;
• and
• generating, with an oscillator of the phase-locked loop, a clock signal having a phase that is based at least on the filtered control signal.

A phase-locked loop, comprising:

• a phase error detector configured to receive an input signal and a feedback signal of the phase-locked loop and output a phase error signal reflecting a difference between a phase of the input signal and a phase of the feedback signal;
• an event detector configured to detect a loss of lock condition based at least on the phase error signal, and subsequent to detecting the loss of lock condition, detect a lock condition based at least on the phase error signal;
• a loop filter configured to filter the phase error signal to generate a filtered control signal based at least on a first set of one or more filter parameter values;
• and in response to the loss of lock condition, filter the phase error signal to generate a filtered control signal based at least on a second set of one or more filter parameter values different from the first set of one or more filter parameter values, and in response to the subsequent restoring of the lock condition, filter the phase error signal to generate the filtered control signal based at least on a first set of one or more filter parameter values;
• and
• an oscillator configured to output an output signal having a phase that is based at least on the filtered control signal.