Voltage level control for d. c.-to-d. c. converter

Claim 1

A D.C.-to-D.C. converter for receiving an input voltage at one potential from a two terminal source of input voltage and supplying an output voltage at another potential comprising: a resonant transformer having a center tapped primary winding coupled to one terminal of the source of input potential and at least one secondary winding; a current switch with three transistors, two of the transistors being switching transistors with their collectors connected to opposite ends of the center tapped primary winding to supply current to the primary winding, their emitters coupled together and floating with respect to both terminals of said sources of input voltage and their bases being coupled to the mentioned secondary winding to receive voltages therefrom and cause the two switching transistors to operate in class C mode of operation and the third transistor serving as a current source for the two switching transistors with its collector connected to the emitters of the two switching transistors and its emitter coupled to the other terminal of the source of the input voltage so that said other terminal functions as a ground terminal for the D.C.-to-D.C. converter; and control means for regulating the output voltage of the converter including: differential sensing means floating on the potential at the center tap of the transformer for comparing the voltage between the center tap and at least one end of the primary winding to a fixed voltage and for providing an output voltage indicative of the difference in potential between the two compared voltages; and control transistor means coupling the output of the differential amplifier to the base of the third transistor to control the magnitude of the current through the third transistor as a function of said output, said control transistor means including means for referencing the output voltage of said differential amplifier to ground potential for the D.C.-to-D.C. converter.