Patent ID: 6163328
Filing Date: 2000-12-19
Classification: H03L,H04N

Abstract:
An RF driver for providing RF voltage to an external load, comprising:a voltage-controlled oscillator having an oscillator control input, said voltage-controlled oscillator generating a drive signal having a frequency f.sub.VCO, said frequency f.sub.VCO being responsive to an oscillator control signal received at said oscillator control input;an RF driver stage having an RF driver stage input coupled to receive said drive signal and first and second RF driver stage outputs coupled across said external load, said RF driver stage generating said RF voltage at said first and second RF driver stage outputs in response to said drive signal;a current transformer coupled between one of said first and second RF driver stage outputs and said external load, said current transformer sensing a current in a resonant circuit including said external load coupled to said RF driver stage and generating a reference current having the same phase as the sensed current;a phase detector coupled to receive said reference current and said drive signal, said phase detector generating a phase detection signal providing a measure of the phase of said reference current with respect to said drive signal; anda controller coupled to receive said phase detection signal, said controller generating said oscillator control signal in response to said phase detection signal.