Voltage controlled oscillator with gain control

A phase lock loop (PLL) circuit, comprising:

• a VCO having a supply voltage input, a frequency tune input and an output providing a clock, wherein said VCO has a gain that changes with voltage level of said supply voltage input;
• a PLL control circuit having a first input receiving said clock, a second input receiving a reference clock, and an output providing a tune voltage to said frequency tune input of said VCO;
• a voltage supply, having a voltage control input and having a supply voltage output coupled to said supply voltage input of said VCO, that adjusts voltage level of said supply voltage output based on said voltage control input;
• and
• a controller having an adjust output coupled to said voltage control input of said voltage supply, wherein said controller controls said adjust output to control gain of said VCO during operation of the PLL circuit.

A method of controlling gain of a voltage controlled oscillator (VCO), the VCO having a supply voltage input and a gain which varies with voltage level of the supply voltage input, said method comprising:

• operating the VCO within a first frequency range;
• providing a first voltage level to the supply voltage input of the VCO to achieve a first gain level;
• and
• providing, while the VCO is operating, a second voltage level to the supply voltage input of the VCO to achieve a second gain level.