Loss of lock detector for clock and data recovery system

An apparatus comprising:

• a clock and data recovery system;
• and
• a loss of lock detector associated with the clock and data recovery system and configured to generate a loss of lock signal responsive to phase adjustment requests generated for a clock signal in the clock and data recovery system;
• wherein the phase adjustment requests comprise a plurality of phase up requests and a plurality of phase down requests;
• and
• wherein the loss of lock detector comprises an accumulator configured to accumulate absolute values of respective phase increments over an accumulation interval wherein the respective phase increments are associated with respective subsets of the phase up and phase down requests.

An apparatus comprising:

• a clock and data recovery system;
• and
• a loss of lock detector associated with the clock and data recovery system and configured to generate a loss of lock signal responsive to phase adjustment requests generated for a clock signal in the clock and data recovery system;
• wherein the phase adjustment requests comprise a plurality of phase up requests and a plurality of phase down requests;
• wherein the loss of lock detector comprises differencing circuitry configured to compute an absolute value of a phase increment associated with a corresponding subset of the phase up and phase down requests;
• and
• wherein the loss of lock detector comprises delay circuitry configured to control synchronous delay in processing periods of the differencing circuitry responsive to a programmable index offset.

A method comprising:

• generating phase adjustment requests for a clock signal in a clock and data recovery system, wherein generating phase adjustment requests comprises generating a plurality of phase up requests and a plurality of phase down requests;
• and
• generating a loss of lock signal responsive to the plurality of phase up requests and the plurality of phase down requests;
• wherein generating the loss of lock signal comprises processing a request group comprising multiple ones of the phase up and phase down requests so as to replace the request group with a single phase up request if the number of phase up requests in the group exceeds the number of phase down requests in the group and to replace the request group with a single phase down request if the number of phase down requests in the group exceeds the number of phase up requests in the group.

A method comprising:

• generating phase adjustment requests for a clock signal in a clock and data recovery system, wherein generating phase adjustment requests comprises generating a plurality of phase up requests and a plurality of phase down requests;
• and
• generating a loss of lock signal responsive to the plurality of phase up requests and the plurality of phase down requests;
• wherein generating the loss of lock signal comprises:
• accumulating absolute values of respective phase increments over an accumulation interval;
• and
• generating the loss of lock signal as a function of the accumulated phase increment absolute values;
• wherein the respective phase increments are associated with respective subsets of the phase up and phase down requests.

A computer program product comprising a non-transitory storage medium having executable computer program code embodied therein, wherein the computer program code when executed in a processing device causes the processing device to perform the steps of:

• generating phase adjustment requests for a clock signal in a clock and data recovery system, wherein generating phase adjustment requests comprises generating a plurality of phase up requests and a plurality of phase down requests;
• and
• generating a loss of lock signal responsive to the plurality of phase up requests and the plurality of phase down requests;
• wherein generating the loss of lock signal comprises processing a request group comprising multiple ones of the phase up and phase down requests so as to replace the request group with a single phase up request if the number of phase up requests in the group exceeds the number of phase down requests in the group and to replace the request group with a single phase down request if the number of phase down requests in the group exceeds the number of phase up requests in the group.