Oscillator with frequency variation compensation

A method for controlling a phased-locked loop (PLL) with a voltage controlled oscillator, the method comprising:

• receiving a selection signal indicating a selected frequency band;
• causing the voltage controlled oscillator to generate an oscillating signal in the selected frequency band;
• measuring a frequency drift in the oscillating signal caused by an environmental change to the PLL;
• applying a first analog control signal to a first varactor of the voltage controlled oscillator, wherein the first varactor is biased by a first bias voltage;
• and
• applying the first analog control signal to a second varactor of the voltage controlled oscillator to change a frequency of the oscillating signal, wherein the second varactor is biased by a second bias voltage, the second bias voltage being a different voltage than the first bias voltage;
• and
• applying a second analog control signal to a third varactor of the voltage controlled oscillator to compensate for the frequency drift, wherein the first and second analog control signals are different voltages.

An electronic system for producing an oscillating signal, the electronic system comprising:

• a transceiver compliant with the Bluetooth standard;
• an inductor-capacitor (LC) tank resonator circuit comprising at least of an inductor, a capacitor, and a first varactor, wherein the first varactor is coupled to a first voltage control signal;
• a signal source coupled to the LC tank resonator to sustain an oscillating signal;
• a linear adjustment circuitry coupled to the LC tank resonator circuit, the linear adjustment circuitry comprising a second varactor coupled to the LC tank resonator, wherein the second varactor is coupled to a second voltage control signal, and the first and second voltage control signals are the same voltages;
• a frequency compensation circuitry coupled to the LC tank resonator, the frequency compensation circuitry comprising a third varactor, wherein the third varactor is coupled to a third voltage control signal, and the first and third voltage control signals are different voltages;
• and
• a controller configured to:
• cause the LC tank resonator circuit to generate the oscillating signal in a selected frequency band;
• cause the linear adjustment circuitry to adjust a voltage sensitivity of the electronic system to be linear;
• cause the frequency compensation circuitry to modify a frequency of the oscillating signal;
• and
• provide the oscillating signal to the transceiver.