Hybrid fractional-N sampling phase locked loop (PLL) with accurate digital-to-time converter (DTC) calibration

A device comprising:

• a voltage-controlled oscillator having a proportional control input and an integral control input;
• a sampling phase detector having an output that supplies a control signal for the proportional control input to the voltage-controlled oscillator;
• a digital-to-time converter connected to an input of the sampling phase detector;
• a reference frequency generator that supplies a reference frequency clock signal to the sampling phase detector via the digital-to-time converter;
• and
• a digital-to-time converter control loop, comprising a comparator that compares the output of the sampling phase detector to a reference voltage, that controls an input of the digital-to-time converter,
• wherein the output of the comparator also supplies the control signal to control the integral control input of the voltage-controlled oscillator, and
• wherein a circuit path between the comparator and the integral control input of the voltage-controlled oscillator is devoid of a transconductance amplifier.

A device comprising:

• a voltage-controlled oscillator;
• a digital-to-time converter that is controlled by a digital-to-time converter calibration loop, the digital-to-time converter calibration loop having a comparator configured to receive an output of a sampling phase detector of a phase locked loop, the output of the sampling phase detector of the phase locked loop also being supplied as a control source for a proportional control input of the voltage-controlled oscillator;
• the digital-to-time converter calibration loop further configured to receive an output of the comparator and to provide a digital input to the digital-to-time converter, which provides an input to the sampling phase detector;
• and
• an output of the comparator configured to supply a control source for an integral control input of the voltage-controlled oscillator,
• wherein a circuit path between the comparator and the integral control input of the voltage-controlled oscillator is devoid of a transconductance amplifier.