Programmable VCO, method of calibrating the VCO, PLL circuit with programmable VCO, and setup method for the PLL circuit

A phase-locked loop circuit, comprising:

• a phase/frequency detector;
• a loop filter connected to the phase/frequency detector;
• a voltage-controlled oscillator with a voltage input and an output, the voltage input being connected to the loop filter;
• a first feedback loop from the output to the phase/frequency detector;
• the voltage-controlled oscillator being enabled to be electrically disconnected from the loop filter and from the first feedback loop;
• the voltage-controlled oscillator comprising a trimming circuit and a current-controlled oscillator, wherein the trimming circuit is configured to:
• provide an input current for the current-controlled oscillator, and
• provide a reference voltage;
• and
• a second feedback loop configured to apply the reference voltage to the voltage input selectively;
• the trimming circuit being programmable;
• and
• the trimming circuit being configured to derive the input current from a first programming code and a second programming code, which is independent of the first programming code.

A setup method for a phase-locked loop circuit comprising a phase/frequency detector, a loop filter connected to the phase/frequency detector, a voltage-controlled oscillator with a voltage input and an output, the voltage input being connected to the loop filter, and a first feedback loop from the output to the phase/frequency detector, comprising:

• disconnecting the voltage-controlled oscillator from the loop filter and from the feedback loop;
• generating a reference voltage using a trimming circuit of the voltage-controlled oscillator;
• applying the reference voltage to the voltage input using a second feedback loop;
• applying a first programming code;
• iteratively adjusting the first programming code until a desired center frequency is obtained;
• applying a second programming code while maintaining the adjusted first programming code applied;
• iteratively adjusting the second programming code until a desired gain is obtained;
• and
• connecting the voltage-controlled oscillator to the loop filter and to the feedback loop, so that the phase-locked loop circuit is ready for normal operation.

A phase-locked loop circuit, comprising:

• a phase/frequency detector;
• a loop filter connected to the phase/frequency detector;
• a voltage-controlled oscillator with a voltage input and an output, the voltage input being connected to the loop filter;
• a first feedback loop from the output to the phase/frequency detector;
• the voltage-controlled oscillator comprising a trimming circuit and a current-controlled oscillator, wherein the trimming circuit is configured to:
• provide an input current for the current-controlled oscillator, and
• provide a reference voltage;
• and
• a second feedback loop configured to apply the reference voltage to the voltage input selectively;
• the trimming circuit being programmable and configured to derive the input current from a first programming code and a second programming code, which is independent of the first programming code;
• and
• switches configured to allow a temporary disconnection of the voltage-controlled oscillator from the loop filter and from the first feedback loop, a temporary application of the reference voltage to the voltage input of the voltage-controlled oscillator, and an alternative connection of the first programming code and the second programming code to the trimming circuit.