Phase-locked loop circuit, corresponding radar sensor, vehicle and method of operation

A circuit, comprising:

• a phase-frequency detector configured to generate first and second digital control signals indicative of phase differences between an input reference signal and an output signal;
• a charge pump configured generate a control signal based upon the first and second digital control signals;
• an oscillator circuit comprising:
• an active core coupled between first and second nodes;
• and
• a tunable resonant circuit comprising an inductance coupled between the first and second nodes, first and second variable capacitances coupled between the first and second nodes, and a set of capacitances selectively connected between the first and second nodes, wherein a tap between the first and second variable capacitances receives the control signal for tuning the tunable resonant circuit;
• a timer circuit configured to generate a timing signal based upon the input reference signal and a reset signal;
• and
• a calibration circuit configured to control which capacitances of the set of capacitances are connected between the first and second nodes, in response to the timing signal and a comparison between a threshold and a voltage signal, the voltage signal being based upon auxiliary pulsed currents generated based upon the first and second digital control signals.