a double resonance voltage converter and method of operating such a converter having : a switching circuit with a first switch and a second switch ; a double resonance resonant circuit having a series resonant circuit and a parallel resonant circuit ; a rectifying and filtering circuit , and a control circuit for controlling the switching circuit having two state arrangements . a first arrangement controls the conducting states of the switching circuit and a second arrangement controls the start of the first arrangement . the converter may be used to obtain very high voltages , on the order of 100 kilovolts and more , for providing power to an x - ray tube in a radiological imaging apparatus .