Automatic calibration of a ring phase locked loop

A method of automatically calibrating a phase locked loop (PLL), the method comprising:

• providing an output signal from an output of a voltage-controlled oscillator (VCO);
• determining a first counter value based on an output frequency of the output signal;
• determining a second counter value based on a target frequency;
• determining a clock difference between the first counter value and the second counter value;
• and
• changing the output frequency of the output signal based on the clock difference.

A non-transitory computer-readable medium containing thereon instructions for calibrating a phase locked loop (PLL), the instructions when executed causing at least one processor to:

• determine a first counter value corresponding to an output frequency of an output signal of a voltage-controlled oscillator (VCO);
• determine a second counter value corresponding to a reference frequency of a reference signal;
• determine a difference between the first counter value and the second counter value;
• and
• responsive to determining that the difference is non-zero, alter a voltage provided to an input of the VCO to change the output frequency of the output signal.