1. A feedback controlled coil driver ( 500 ) comprising: an LC tank circuit ( 512 , 514 ); a direct current power source ( 501 ) coupled to the LC tank circuit; a switch ( 516 ) interconnected between the LC tank circuit and ground to switchably couple the LC tank circuit between the power source and ground when the switch is turned on, wherein the point of interconnection between the LC tank circuit and the switch provides a coil driver output voltage VL ( 504 ); a sample and hold circuit ( 534 ) arranged to monitor the VL; an integrator circuit ( 541 ) configured to provide a voltage VIO ( 542 ) equal to the integral over time of the difference between the sampled VL and a prescribed reference voltage ( 536 ); a voltage ramp generator ( 552 ) arranged to provide a ramp voltage ( 554 ) at such time when the switch couples the LC tank circuit to ground; a first comparator ( 550 ) arranged to compare VIO to the ramp voltage; and a switch driver ( 525 ) coupled to the first comparator and arranged to turn the switch off when the ramp voltage exceeds VIO.