Architecture for maintaining constant voltage-controlled oscillator gain

A voltage controlled oscillator comprising:

• a current controlled oscillator having a variable frequency output;
• a first control path for generating a first control current having a first adjustable gain;
• a second control path for generating a second control current having a second adjustable gain;
• a summer for adding the first and second control currents to obtain a summed control current, and for applying the summed control current as an input current to the current controlled oscillator;
• and
• a control sub-circuit for controlling the gain of the first control path as a function of a defined voltage on the second control path to maintain constant the gain of the output of the current controlled oscillator over a given operating range of said current controlled oscillator;
• and
• wherein:
• the first control path includes a first voltage to current converter and a second voltage to current converter;
• said first voltage to current converter has a fixed gain;
• and
• said second voltage to current converter has a variable gain that varies as a function of said defined voltage on the second control path.

A method of operating a voltage controlled oscillator comprising the steps of:

• generating a first control current in a first control path, said first control path having a first adjustable gain;
• generating a second control current in a second control path, said second control path having a second adjustable gain;
• adding the first and second control currents to obtain a summed control current, and applying the summed control current as an input current to a current controlled oscillator, the current controlled oscillator having a variable frequency current output;
• and
• controlling the gain of the fist control current as a function of a defined voltage on the second control path to maintain constant the gain of the voltage controlled oscillator over a given operating range of said voltage controlled oscillator;
• and
• wherein the second control path includes a voltage-to-current converter, said defined voltage is an output voltage of said voltage-to-current converter, and the controlling step includes the step of applying said output voltage of the voltage-to-current converter to the first control path to control the magnitude of the first control current.