Digital on-time generation for buck converter

A system, comprising:

• a power stage of a voltage converter, the power stage comprising:
• a high-side switch adapted to be coupled to an input voltage source;
• a low-side switch coupled to the high-side switch and to a ground terminal;
• and
• a control circuit configured to control the high-side switch and the low-side switch;
• and
• an apparatus coupled to the power stage, the apparatus comprising:
• a phase frequency detector having a detector output and first and second inputs, the phase frequency detector configured to provide a phase difference signal at the detector output responsive to a reference clock signal received at the first input and a high-side ON signal received at the second input, the high-side ON signal also provided to the control circuit;
• a gain controller having a controller input and a controller output, the controller input coupled to the detector output, and the gain controller configured to:
• provide a first digital value at the controller output based on the phase difference signal;
• and
• provide a second digital value at the controller output based on the phase difference signal and a duty cycle of the voltage converter;
• a first pulse generator having first and second inputs and an output, the first input of the first pulse generator coupled to the controller output, the second input of the first pulse generator adapted to receive the high-side ON signal, the first pulse generator configured to provide a first generator signal at the first pulse generator output responsive to the high-side ON signal and the first digital value;
• and
• a second pulse generator having first and second inputs and an output, the first input of the second pulse generator coupled to the controller output, the second input of the second pulse generator coupled to the output of the first pulse generator, the second pulse generator configured to provide a second generator signal at the second pulse generator output responsive to the first generator signal and the second digital value.

A method of controlling a voltage converter, the method comprising:

• determining a phase difference between a first signal and a second signal;
• determining a duty cycle of the voltage converter;
• generating a digital value based on the phase difference and the duty cycle;
• and
• controlling an ON-time of a switch of the voltage converter based on the digital value.