Phase-locked loop outputs with reduced reference spurs and noise

A circuit comprising:

• a control signal generation unit configured to generate a control signal based on a phase difference between an output signal and a reference signal, the control signal including an alternating current component;
• a feed-forward network comprising a voltage regulator coupled to the control signal generation unit and configured to receive the control signal and to generate a reference voltage signal that includes at least a portion of the alternating current component of the control signal as received from the control signal generation unit;
• and
• a voltage-controlled oscillator coupled to the control signal generation unit and to the voltage regulator, and configured to generate a tuning signal based on the control signal and the reference voltage signal generated by the feed-forward network and configured to generate the output signal based on the tuning signal.

A circuit comprising:

• a control signal generation unit configured to generate a control signal based on a phase difference between an output signal and a reference signal, the control signal including an alternating current component;
• and
• a voltage-controlled oscillator coupled to the control signal generation unit and configured to:
• receive the control signal from the control signal generation unit,
• generate a tuning signal based on the received control signal and a reference voltage signal that includes at least a portion of the alternating current component of the control signal, and
• generate the output signal based on the tuning signal.

A method to reduce noise in an output of a phase-locked loop, the method comprising:

• generating a control signal based on a phase difference between an output signal and a reference signal, the control signal including an alternating current component;
• generating a reference voltage signal that includes at least a portion of the alternating current component of the control signal;
• generating a tuning signal based on the control signal and the reference voltage signal;
• and
• generating the output signal based on the tuning signal.