Locked loop circuit and method with digitally-controlled oscillator (DCO) gain normalization

A method of operation in a locked-loop circuit, comprising:

• comparing an input reference timing signal to an output timing signal from a digitally-controlled oscillator (DCO) to create a difference value, and converting the difference value to a digital value;
• digitally filtering the digital value with a digital loop filter to generate filtered output bits representing a digital value;
• receiving the filtered output bits with the DCO, the DCO to generate the output timing signal in response to the received filtered output bits, the DCO having an anticipated DCO gain representing change in the digital value versus change in the output timing signal;
• during a calibration mode of operation,
• measuring an actual DCO gain,
• determining a scaling factor based on a ratio of the measured actual DCO gain to the anticipated DCO gain, and
• storing a value representing the scaling factor in storage;
• and
• during a run-time mode of operation,
• retrieving the stored value to normalize the actual DCO gain to the anticipated DCO gain.

A digitally-controlled oscillator circuit for use in a locked-loop circuit, comprising:

• a digitally-controlled oscillator (DCO) to receive a digital value from a digital loop filter, the DCO to generate a periodic signal in response to the digital value;
• the DCO having an anticipated DCO gain representing change in the digital value versus change in the periodic signal;
• calibration logic operative during a calibration mode of operation to measure an actual DCO gain and to determine a scaling factor based on the measured actual DCO gain, the scaling factor utilized during a run-time mode of operation to normalize loop filter coefficients to match the anticipated DCO gain;
• and
• storage to store a value representing the scaling factor, wherein the scaling factor is retrievable from the storage prior to the run-time mode of operation.