An enhancement mode JFET as a switching device in a buck-boost converter circuit combined with a single rectifier diode and an inductor. A control circuit coupled to the gate of the JFET switches the JFET between a current conducting state and a current blocking state. The ratio of converter output voltage to converter input voltage is determined by the ratio of JFET current blocking time to the sum of JFET conduction time and JFET blocking time. This pulse width modulation scheme is thus used to adjust the dc output voltage level.